Since multipart RAR files are often hosted on cloud drives by independent technicians, you may find the required part or a complete alternative at the following locations:

: Ensure the firmware matches your 3840x2160 resolution. Installing firmware for a different resolution (like 1080p) can result in a distorted or "mirrored" image.

Searching for the specific "part5.rar" file for the MS638 PC822

: You must have all parts (part1, part2, etc.) in the same folder to extract the final .bin or .img file using WinRAR or 7-Zip.

: If you successfully install the firmware, the factory service code for this board is typically Menu + 1147 . TP.MS338.PC822 USB Firmware Software Bios Bin