Installing firmware via USB is the standard way to recover or update these "China Universal" boards: Use a USB flash drive formatted to FAT32 .
Turn off the TV and unplug it from the power source. Insert USB: Plug the flash drive into the TV's USB port. Download RR8501 C031F 1366x768 USB rar
You can find firmware files (often in .rar or .zip format containing the .bin file) from these community repositories: Installing firmware via USB is the standard way