Schematic PDF with an uninformative name, A21S, that does not identify the brand, model or board number, so it is best matched by opening the document and checking the board code printed on its title blocks. At 6.22 MB it is likely a full circuit diagram. Schematics are used to trace power rails, follow signal paths and identify which component sits on a shorted line. Any PDF viewer opens it. Compare the board number and revision in the drawings with the PCB before relying on it for repair.
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 @schematic_mobile5. 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.