Small 433 KB archive named AO4601, which matches an Alpha and Omega Semiconductor dual MOSFET part number, so it most likely contains its datasheet. Datasheets give the pinout, channel configuration, voltage and current ratings and package outline, which a technician needs when testing a suspected shorted transistor or choosing a substitute. Compare the marking on the chip and the package type with the datasheet before replacing, as similar codes may differ in polarity or ratings.
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 @schematicslaptop. 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.