The file is typically provided in a .rar or .zip format containing a .bin file, which you then copy to a USB drive for installation on your LED/LCD TV board.
To make sure you get the exact right file, could you tell me: Download R85 A81 1366X768 rar
The T.R85.A81 firmware for a 1366X768 resolution panel can be downloaded from electronic repair forums that specialize in universal board software. The file is typically provided in a