Lenovo schematic for board NM-D451, a PDF packed in a 3.13 MB RAR archive. Board numbers in the NM-xxxx format come from LCFC, Lenovo's own ODM in Hefei that designs many of its notebook mainboards. The schematic shows power rails, the EC and power-on sequence, connector pinouts and component values, useful when tracing a no-power or no-display fault. No revision appears in the name, so check the revision marking on the PCB against the title block of the sheets before relying on the drawing.
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 @cyberlanelectonik. 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.