Select > eRecovery mode > Download update and recover .
Press and hold simultaneously until the "Software Upgrade" screen appears. Select > eRecovery mode > Download update and recover
You can find the official flash files and drivers at the following reputable sites: Provides direct downloads for C431 stock ROMs (Android 9 and 10). Select > eRecovery mode > Download update and recover
Extract the downloaded firmware and move the file (and any required data zips) into the dload folder. Power off your phone. Select > eRecovery mode > Download update and recover