Keep holding the button until you see a flashing LED indicator or an "Upgrading software, please do not turn off" screen.
However, many users run into a major roadblock: the system prompts for an or encryption key before it allows the installation to proceed. Allappupdate.bin Password
If this is for an automotive system (like a Pioneer, Kenwood, or Android Head Unit), the password is often found in the "System Information" section of your owner’s manual. The Risks of Using Unofficial Passwords Keep holding the button until you see a
Головные устройства Unisoc на процессоре UIS7862(s) / ... - 4PDA or Android Head Unit)
With that information, I can help you find the precise keys or flashing steps needed for your situation.