Lenovo schematic in PDF form, labelled only with the code 80A, so the exact model and board number cannot be confirmed from the name. At 1.16 MB it should open in any PDF reader, where the netlist text can usually be searched for signal names and reference designators. A technician would use it to follow power sequencing, check rail voltages and find the components around a short. Match the board number silkscreened on the motherboard against the title block before relying on it.
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 .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.