Do not attempt to flash a "Huawei MatePad 10.4 custom ROM 2021" today unless:

The Better Path: Use Huawei's "MicroG" or "Gspace" (virtual Android environment) available on AppGallery in 2024. It simulates Google Play without bricking your device.

Assuming you have an unlocked bootloader and Fastboot access.

Pre-requisites:

The Process:

  • Reboot: fastboot reboot.

    • Post-Flash (2021 specific fix):
    The first boot takes 5-10 minutes. On LineageOS GSI, you must flash a "Huawei audio fix" via fastboot, otherwise speakers output static noise.

    Here is the harsh truth. To flash any custom ROM on the Huawei MatePad 10.4, you need an unlocked bootloader.

    If you missed that window, your tablet likely remains locked to HarmonyOS/EMUI. No 2021 custom ROM works without this step.