No. ASUS never released official Nougat for the Snapdragon 615-based Z00UD. Unofficial custom ROMs exist (e.g., LineageOS 14.1), but they break some camera features.
Let’s be realistic: The Z00UD is a legacy device. Here’s an honest take on using ASUS ZenFone Selfie Z00UD firmware 6.0.1 today:
The firmware shipped with an updated ZenUI skin.
Even with careful steps, you may encounter issues. Here’s a troubleshooting table for the ASUS ZenFone Selfie Z00UD firmware 6.0.1:
| Error Message | Cause | Solution |
|---------------|-------|----------|
| “E: footer is wrong” | Corrupt zip or wrong model | Redownload from ASUS. Verify file size. |
| “Status 7” | Assert failed – firmware not for Z00UD | Check model number in fastboot: fastboot getvar product |
| Stuck at ASUS logo | Dirty flash or cache issue | Boot recovery, wipe data/factory reset, then reboot. |
| WiFi / Bluetooth not working | Mismatched bootloader or modem | Reflash only the modem partition: fastboot flash modem modem.bin |
| Boot loop after update | Incompatible app data | Boot safe mode (Power + Vol Down on logo) and uninstall suspect apps. |
In the mid-2010s, smartphone manufacturers engaged in an escalating arms race, not just for processing power or screen resolution, but for the often-neglected front-facing camera. The ASUS ZenFone Selfie (model Z00UD) emerged as a direct response to this demand, carving a niche for itself with its high-resolution dual cameras. While the phone launched with Android 5.0 Lollipop, its subsequent update to firmware version 6.0.1 (Marshmallow) marked a pivotal moment in its lifecycle. This update did not merely introduce cosmetic changes; it represented a fundamental maturation of the device, refining its signature selfie capabilities, unlocking granular user control, and significantly stabilizing system performance.
The most profound impact of the Marshmallow 6.0.1 update on the ZenFone Selfie was the introduction of the new permissions model. Before this firmware, installing an application meant granting it a blanket set of permissions—a flashlight app could, in theory, request access to your contacts and location. With Android 6.0.1, users gained the ability to grant or revoke permissions on an individual, as-needed basis. For a phone marketed on its front camera, this was crucial. A user could confidently install a third-party beauty or editing app, allowing it access to the 13-megapixel selfie shooter while denying it access to the microphone or storage beyond the gallery. This shifted the power dynamic from the application to the individual, aligning perfectly with the user-centric philosophy of a "selfie" device.
Beyond security, the firmware overhaul delivered tangible enhancements to the user experience, directly leveraging hardware that had been historically underutilized. The ZenFone Selfie Z00UD, powered by a Snapdragon 615 octa-core processor, had sometimes struggled with thermal management and battery drain under Lollipop. Android 6.0.1 introduced Doze Mode, a low-power state that put the device into a deep sleep when it was stationary and not being used. This was transformative for the 3000mAh removable battery, as it drastically reduced background activity during idle periods. The result was a phone that could easily last a full day of heavy social media use, rather than requiring a mid-afternoon recharge.
Furthermore, the update finally brought native support for MicroSD cards as adoptable storage. The ZenFone Selfie targeted a budget-conscious audience that valued media creation—high-resolution photos and videos take up significant space. With adoptable storage, a user could insert a high-speed microSD card and format it to function as an extension of the internal storage, allowing apps, games, and their data to reside on the external card seamlessly. This was a practical godsend, effectively allowing a 16GB or 32GB model to expand functionality without the constant "insufficient storage" warnings that plagued many 2015-era devices.
However, the transition to 6.0.1 on the Z00UD was not without its growing pains. Users on ASUS’s official ZenTalk forums frequently reported early issues, including a "ghost touch" bug that affected screen responsiveness after the update and an aggressive battery optimization that sometimes killed push notifications for essential apps like email or WhatsApp. ASUS’s ZenUI overlay, while feature-rich, remained a heavy skin that clashed with the cleaner "Material Design" aesthetic of stock Marshmallow, leading to a sense of software dissonance. Nevertheless, ASUS diligently pushed incremental patches (e.g., firmware version 6.0.1.235) that eventually resolved the critical bugs, solidifying Marshmallow as the most stable and reliable operating system the device ever received.
In conclusion, the Android 6.0.1 firmware for the ASUS ZenFone Selfie Z00UD was far more than a routine maintenance update. It was the key that unlocked the phone's latent potential. By introducing fine-grained privacy controls, battery-saving doze functionality, and flexible adoptable storage, Marshmallow rationalized the hardware, transforming a promising but flawed mid-ranger into a genuinely reliable daily driver. While later models would offer superior processors and sleek glass sandwiches, the Z00UD on its final stable Marshmallow build stands as a testament to a specific era of smartphone design—one where software updates could fundamentally redeem a device and deliver on the marketing promise of creating a phone truly built for its user, selfie camera first.
Asus Zenfone Selfie (ZD551KL / Z00UD) Firmware 6.0.1 Marshmallow Update Guide
The Asus Zenfone Selfie, known by its model number Z00UD, remains a favorite for users who appreciate its dedicated front-facing flash and high-quality camera sensors. Updating to Android 6.0.1 Marshmallow is the best way to improve system stability, optimize battery life, and ensure app compatibility.
This guide provides everything you need to know about finding and installing the official firmware for your device. Firmware Details
Device Name: Asus Zenfone SelfieModel Number: ZD551KL (Z00UD)Android Version: 6.0.1 MarshmallowBuild Number: WW-21.40.0.2214 (or later)Region: WW (Worldwide) Key Features of Marshmallow 6.0.1
Doze Mode: Significantly improves standby battery life by hibernating background apps.Now on Tap: Provides contextual information based on what is currently on your screen.App Permissions: Grants you granular control over what data your apps can access.Enhanced Performance: Smoother UI transitions and optimized RAM management for the Snapdragon 615 chipset. Prerequisites Before Flashing
Backup Your Data: Flashing firmware can sometimes lead to data loss. Save your photos, contacts, and messages.
Battery Level: Ensure your phone has at least 60% charge to prevent shutdown during the process.
Check Your SKU: Go to Settings > About > Software Information. Ensure your Build Number starts with "WW." You must match your current SKU (WW to WW).
Storage Space: Ensure you have at least 2GB of free internal storage. How to Install Asus Zenfone Selfie 6.0.1 Firmware Method 1: The Local Update (Recommended)
Download the Firmware: Locate the official .zip firmware file for the ZD551KL from the Asus support website.
Transfer the File: Connect your phone to your PC and move the downloaded .zip file to the root directory of your phone’s internal storage (do not put it in a folder).
Trigger the Update: Disconnect the USB cable. A notification should appear in the status bar saying "System Update File Detected."
Confirm: Tap the notification and follow the on-screen prompts. The phone will reboot and begin the installation. Method 2: Recovery Mode (Sideload)
If your phone is bootlooping or the local update fails, use this method: Power off your device. asus zenfone selfie z00ud firmware 6.0 1
Press and hold Volume Down + Power Button to enter Recovery Mode.
Select "Apply update from ADB" or "Apply update from microSD."
If using a microSD, select the firmware file from your card and confirm. Once the process hits 100%, select "Reboot system now." Troubleshooting Common Issues
Update Notification Not Appearing: Ensure the file name has not been changed. It must remain exactly as downloaded from Asus. Also, double-check that the file is in the root directory, not the "Download" folder.Stuck on Asus Logo: This is common after a major version jump. Boot into recovery and perform a "Wipe Cache Partition."Downgrade Issues: Moving from Marshmallow back to Lollipop is difficult and usually requires a factory reset and specific downgrade tools.
By updating your Asus Zenfone Selfie Z00UD to Android 6.0.1, you breathe new life into the hardware, making the camera experience snappier and the overall interface more secure. Always ensure you are using the official WW firmware to avoid bricking your device.
Asus ZenFone Selfie (Z00UD/ZD551KL) firmware 6.0.1 (Marshmallow)
is widely regarded as a significant improvement over the original Lollipop software, primarily due to the removal of excessive "bloatware" and better overall system stability. The "Good" in Version 6.0.1 Reduced Bloatware
: The update removes nearly 20 pre-installed apps (like Mirror, Omlet, and Asus MyFrame), which frees up system resources and simplifies the user interface. Performance Stability
: Users report that the device runs "smoothly like butter" on 6.0.1, with improved RAM management and a faster overall feel compared to previous versions. Enhanced Camera Features
: While the hardware remains the same, the 6.0.1 firmware adds new software modes like Pano Sphere and better motion gesture support. New Google Integrations
: The update replaces several redundant Asus apps with standard Google versions, such as Google Calendar and Google Messenger. Key Considerations Before Updating App2SD Support : A major drawback of the 6.0.1 update is that it removes the ability to move apps to the microSD card
. You must move any apps currently on your SD card back to internal storage before updating. Manual Installation
: For many users, this update does not arrive automatically over-the-air (OTA) and requires downloading the ~1.63GB firmware file from the official ASUS support site to flash manually. Battery Life
: While performance is better, battery life remains "average" at 3,000 mAh, though the more efficient Snapdragon 615 handling in Marshmallow helps slightly. Summary of User Experience Verdict on 6.0.1 System Speed : Much faster than Lollipop. : Less bloat, but no more App2SD. Selfie Quality : 13MP front sensor remains top-tier for its class. Reliability : Stability is notably improved in the .2156 version. step-by-step instructions on how to manually flash this specific firmware version? Asus Zenfone Selfie ZD551KL - User opinions and reviews
The Asus ZenFone Selfie (Z00UD/ZD551KL) Go to product viewer dialog for this item.
update to Android 6.0.1 Marshmallow is widely considered a essential upgrade for performance, primarily because it removes a massive amount of "bloatware" that plagued the original Lollipop version. 🚀 Performance & Software
The shift to firmware version 21.40.0.1692 (or later) significantly cleans up the user interface.
Bloatware Removal: Asus removed over 20 pre-installed apps, including Mirror, Omlet, Party Link, and PC Link, freeing up internal storage and system RAM.
System Fluidity: Users report the Snapdragon 615 processor runs "smoothly like butter" after the update, effectively resolving the sluggishness seen on older firmware.
Marshmallow Features: Adds Doze Mode for better standby battery, Google Now on Tap, and granular App Permissions. 📸 Camera Experience
The hardware remains the standout feature, but the software update improves the processing of its dual 13MP cameras.
Selfie Quality: High-resolution 13MP front shots with a dual-tone flash remain excellent for its class.
Autofocus: The rear laser autofocus provides 0.2-second focus speeds, though some users find the camera rattles slightly due to its physical design.
Drawback: Fancy photo-processing modes (like HDR or Super Resolution) can still be slow/sluggish even on 6.0.1. 🔋 Battery & Hardware Asus Zenfone Selfie ZD551KL - User opinions and reviews In the mid-2010s, smartphone manufacturers engaged in an
The notification arrived on a Tuesday, thin as a whisper: “System Update: Android 6.0.1 (Marshmallow) – 1.21 GB.”
Lena stared at her ASUS ZenFone Selfie’s screen. The phone, a lavender-gray brick with a charmingly ridiculous 13-megapixel front camera, had been her loyal companion for two years. It had survived a drop into a bowl of ramen broth and a winter stuck on Android 5.0 Lollipop. Lollipop was reliable—clunky, battery-hungry, but reliable.
But this update, labeled WW_6.0.1_23.40.0.3_20170112, promised change. “Do you want to install?” it asked.
She tapped “Yes.”
The phone rebooted. The ASUS logo glowed. Then, the little green android appeared, belly-up, with a spinning blue wireframe globe on its chest. The progress bar crawled. 10%. 30%. 50%. Lena made tea. 80%. She checked Instagram on her laptop. 99%.
Then, silence.
The screen went black. Not the “off” black—the void black. A tiny red LED blinked near the earpiece, like a dying heartbeat.
“No. No, no, no,” she whispered.
She pressed the power button. Nothing. Power + Volume Up. Nothing. She plugged it in. The LED glowed solid red for a moment, then returned to its slow, desperate blink. Her Selfie was a brick. A pretty lavender-gray paperweight.
Three hours of frantic Googling later, she found them: the ghosts of XDA Developers.
A thread titled "[GUIDE] Unbrick Z00UD – Raw Firmware Flash (6.0.1)" was her only hope. The instructions were a ritual of desperation:
At 2:00 AM, her laptop screen flickered. Device Manager refreshed. A new device appeared: "Cloverview Plus" with a yellow exclamation mark.
She had entered the DNX mode—the phone's deepest emergency bootloader. A place most users never see.
The command line was her language now. She typed:
> fastboot flash boot boot.img
> fastboot flash system system.img
> fastboot flash recovery recovery.img
Each command felt like defusing a bomb. The phone's tiny red LED would flash faster with every successful write. Finally, the last line:
> fastboot reboot
The screen glowed. The ASUS logo returned, but it was sharper, cleaner. Then, the new setup wizard appeared—Android 6.0.1 Marshmallow, with its fresh "M" logo and simplified icons.
The first thing Lena noticed was Doze. The battery graph was a gentle slope, not a cliff. The second was App Permissions—no more flashlight apps asking for her contacts. The third, and most personal, was the Selfie Master app. The front camera’s 13MP sensor, now optimized for Marshmallow, captured skin tones that actually looked like skin.
She took a deep breath. The phone, once dead, was reborn.
That night, she wrote a new post on XDA: “Fixed my Z00UD. Don’t give up on your Selfie. Marshmallow is worth the nightmare.”
Her phone didn't just have new firmware. It had a second life.
The End.
The official Android 6.0.1 Marshmallow firmware for the ASUS ZenFone Selfie (Z00UD / ZD551KL) is version V21.40.0.1999. Firmware Details Model Name: ASUS ZenFone Selfie (ZD551KL) Model Number: Z00UD Android Version: 6.0.1 (Marshmallow) Build Number: WW_21.40.0.1999 Region: Worldwide (WW) Official Download Link The notification arrived on a Tuesday, thin as
You can find the firmware file directly on the ASUS Support Website. Installation Instructions
Check Version: Ensure your device is currently running the latest Android Lollipop version before jumping to Marshmallow. Download: Download the .zip file (do not unzip it).
Transfer: Connect your phone to your PC and move the file to the internal storage root directory (not inside any folder).
Update Notification: Disconnect the cable. A "System Update File Detected" notification should appear in your status bar.
Install: Tap the notification and follow the prompts. Ensure your battery is above 15% and you have backed up your data.
Note: Upgrading to Android 6.0 will remove APP2SD support. Move any apps stored on your SD card back to internal storage before updating.
The official Android 6.0.1 (Marshmallow) firmware for the ASUS ZenFone Selfie (model Z00UD / ZD551KL)
is the final major update officially supported for this device. Firmware Details Model Compatibility : ZenFone Selfie ZD551KL (Z00UD). : Android 6.0.1 Marshmallow. SKU Matching
: Updates must match the device's SKU (e.g., WW, CN, JP). Installing a different SKU may lead to permanent device failure. Official Availability
: While Over-the-Air (OTA) updates were standard, manual downloads are often required for older devices through the ASUS Download Center Update Methods 1. Over-the-Air (OTA) Update Settings > About > System update Check Update Requirements
: Stable Wi-Fi and at least 60% battery life are recommended before starting. 2. Manual Update (Internal Storage) Preparation : Download the correct firmware file from the official ASUS Support site Installation file in the root directory of the phone's internal storage (not inside any folder).
Reboot the phone. A "System update file detected" notification should appear in the status bar.
Tap the notification and follow the on-screen prompts to install. 3. Manual Update (SD Card/Recovery Mode)
: Place the firmware file on a microSD card. Reboot the phone into Recovery Mode and select Apply update from SD card Optimization
: After installation, the device will restart and optimize apps, which may take several minutes. Important Precautions Step-by-Step Upgrading
: You cannot jump directly from older versions to 6.0.1; you must install intermediate versions sequentially. Backup Data
: System upgrades can cause data loss. Always back up your important information before proceeding. Recovery Tools
: If an error occurs during the transition from Android 5.0 (Lollipop), specific recovery tools or flashing a standalone recovery file may be necessary. Do you need help identifying your SKU
(e.g., WW or CN) to find the exact download link for your device?
Here’s a ready-to-post guide / announcement for a forum, blog, or social media update regarding the ASUS ZenFone Selfie (ZD551KL / Z00UD) and its Android 6.0 Marshmallow firmware (version 6.0.1).
Rare, but try: Go to Settings > Security > Fingerprint > remove all fingerprints > reboot > re-add.
It is critical to distinguish the Z00UD from other Zenfones.
Once your ZenFone Selfie boots into Android 6.0.1, follow these steps: