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

Copy the firmware file (often named allupgrade_ms.bin or similar) to the root directory of the USB drive. Turn off the TV and unplug the power cord. Insert the USB drive into the TV's USB port.

Flashing a "dump" file (usually an .bin or .img file inside the .rar ) requires a USB drive or a dedicated programmer (like an RT809F/H). Format a USB flash drive (FAT32 filesystem). Extract the contents of the downloaded .rar file.