: This site hosts official manufacturer firmware specifically for the TP.S512.PC821

Do you have the of your DEXP TV or the panel sticker info to ensure this is the exact file you need? Complete TP HV553 PC821 Software Setup Instructions

Press and on the TV panel (not the remote).

: Once the update reaches 100%, the TV may restart automatically or the LED will stop blinking. Unplug the USB drive and power cycle the TV.

: Unzip the package on your PC. You should see a binary file (often named allupgrade_... .bin or similar).