If power is interrupted during the USB flash, the board may become "bricked" and will require a hardware programmer (like the CH341A) to fix. If you'd like, I can help you find:
This report details the firmware requirements and installation process for the RR8501 C031D Download RR8501 C031D 1680x1050 USB rar
The for this board to adjust picture settings. If power is interrupted during the USB flash,
Always backup your original firmware if possible before flashing new software. Download RR8501 C031D 1680x1050 USB rar
Installing the software via USB is the most common way to update these boards.