Since manufacturers rarely host public downloads, use this free method:
This is a classic symptom of flashing the wrong MCU or Kernel. The Android system is working, but the software driving the screen resolution (1024x600) is wrong. You will need to find the correct "Factory Settings" code to try and force a recovery or re-flash the original stock firmware.
The XDA Developers forum is the gold standard for Android head unit modifications.
While Amedia Auto has an official presence, many users rely on community-driven sources for free updates. Here are the most reliable avenues: