ASUS B85M-G desktop motherboard archive in RAR format, 4.49 MB. The name gives the board model but no revision, BIOS version or file type, though at this size a BIOS image or a BIOS image with tools is the most likely payload. The B85M-G uses the Intel B85 chipset. A technician would extract the image and write it to the board's SPI flash with a programmer when the board fails to POST after a corrupt update. Check the PCB revision, back up the existing chip and confirm the image matches the chip size.
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 @biositechyangiyer. 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.