Schematic in PDF format, 2.29 MB, for a device identified only as A800; the name gives no brand, so the exact product cannot be confirmed from the title alone. A PDF circuit diagram like this is opened in any PDF reader and used to follow power lines, locate connectors and test points, and identify parts around charging, display or audio circuits. Compare the model and board markings of the unit on the bench with the pages inside before relying on component values or pin numbers shown in the drawing.
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 @mobileshematic. 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.