TCL 50B2800 television archive in RAR format, 2.36 MB, for a 50-inch class set judging by the model number. The name offers no details about the chassis or the files enclosed. Such material is usually used to follow supply rails, check the LED backlight circuit and recover a mainboard with corrupted firmware. Open with 7-Zip or WinRAR, compare the board numbers printed on the PCB with the documentation, and save a full copy of the original memory before programming any image.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @hashmielecom. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.