PDF document of 16.8 MB filed under schematics, but its name only reads electronic and gives no device, brand, model or board number. The contents cannot be judged from the name, so open it to find out whether it holds a circuit diagram, a service manual or general training material. If it turns out to be a schematic, match the board number in its title block against your PCB before relying on it. A large file size often points to scanned pages, which can make searching for part designators harder.
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 @mobile_jump2. 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.