Schematic in PDF form whose name refers to P552LJ, with an RG suffix that is not explained. The name gives no brand or board number, so confirm the match against the markings printed on the PCB. A schematic like this lets a technician follow power rails from the adapter input through the regulators, check enable and power-good signals, and find component values when replacing failed parts. It opens in any standard PDF viewer, and the 918 KB size suggests a complete document rather than a single page.
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 @pepeelectronica. 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.