Based on your request, the file is a firmware update file (likely V8-S68AT02-LF1V198.bin) designed for specific TCL TV models (E5900, E7800, H9800, Q7700, P2US series).
It is not a part of a multipart .rar archive, but rather a large .bin firmware update file. Download S68AT02 LF1V198 part03 rar
the USB into your TV (use the USB 2.0 port if possible). Unplug the TV from power. Based on your request, the file is a
for the 198 firmware if I search specific firmware forums. Based on your request
Note: A similar, slightly older version (V8-S68AT02-LF1V182.bin) was previously provided officially by TCL Thailand on Dropbox for similar TV series. Download the .bin firmware file from a reputable source. Format a USB flash drive to FAT32 .
for a specific TV model (e.g., Q7700). TCL Electronics - Facebook