Circuit diagram in PDF form for the Lenovo 3000 G550 laptop, about 1.5 MB. The name lists neither the board number nor the revision, so check the title block and compare it with the code printed on the mainboard before working from it. With a matching board, the schematic helps follow the power-on sequence, measure each rail, trace the charging circuit and find the component behind a short. Any standard PDF viewer opens it, and text search speeds up finding net names.
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 @smschematics. 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.