Here is a development review regarding the firmware download and update process for the CV920-E42 platform.
Do not power off the device until the progress bar reaches 100% and the device reboots. AliExpress Key Specifications cv920-e42 firmware download
Advanced voltage regulation to protect against surges. Why You Need a Firmware Download Firmware updates for the CV920-E42 are critical for: Here is a development review regarding the firmware