Lenovo IdeaPad U460 documentation packed as a RAR archive of 1.88 MB and tied to the Compal LA-5941P motherboard. Compal, the ODM behind this board, uses LA-xxxxP numbers, and the same number is printed on the PCB together with a revision. The archive most likely contains the circuit diagram, which is opened with a PDF viewer or a schematic tool after extraction. Use it to follow power rails, the EC and BIOS circuitry and the signal routing, and check that the board number on your unit matches first.
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 @alischematics. 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.