If the USB method fails because the board is completely dead or "Read Time Out" occurs, you may need an to write the software directly to the EMMC chip via JTAG or ISP. This is a professional repair step and requires specific hardware.
: Press and hold the Power button on the TV keypad (not the remote) while plugging the power cord back in.
: The indicator light (usually red/green) will start flashing rapidly. This means the software is being written to the EMMC.