TCL 40F3520 television package, a 6.03 MB RAR archive whose name gives the model and nothing more. The contents could be a main board flash dump, service documentation or both, so unpack it and check before use. TV firmware dumps are normally written to the SPI or eMMC memory on the main board to cure boot loops, a dead standby state or a missing picture. Always read and keep the original chip data first, and confirm that the main board number and panel type match the source set.
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.