Indexed as a schematic, this 145 KB PDF is named 303CNQ and nothing more, with no laptop model, board number or revision. The code resembles a power semiconductor series name, and the file size suits a compact technical sheet. Technicians keep documents like this for pin assignment, package and electrical limits when replacing a failed component. Check the full marking on the device, including any numeric suffix, against what the PDF lists before fitting a replacement.
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.