Archive of Lenovo repair material for the LCFC motherboard NM-B491, revision 1.0, packed as an 8.91 MB RAR. The name does not list the contents, so expect some mix of schematic, boardview or firmware typical of such packs. NM-prefixed numbers follow the LCFC pattern, the Lenovo-owned ODM that builds many IdeaPad and ThinkPad boards. Extract it and confirm the NM-B491 marking and rev 1.0 silkscreen on the PCB before using any diagram to trace power rails or locate components.
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 @ShareMan_Electronic_Files. 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.