Laptop schematic identified only by the number 4520, with no brand, board number or revision stated in the name, so the exact model cannot be confirmed from the title alone. The PDF is 1.83 MB, suggesting a full multi-page circuit set. Open it and check the title block and project code before use. A schematic like this helps a technician trace power rails, read the power-on sequence, measure signals at test points and narrow down a short circuit to a specific component or rail.
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 .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.