Download: V50X_IMX458_20201109_V2.0.zip
Unzip, put the files on the root of your SD card. Plop it in your camera and power up while holding the volume up button. The screen will stay blank for about two minutes but you will see the activity light flashing. When complete, the camera will reboot. I think the camera needs to be plugged in and charging during this process.
Thanks for this! Akaso did not want to provide me with the firmware, saying my device was ‘out of limited warranty’ even though it’s less than 1.5 years old.