Schematic for the Apple logic board 820-2997, provided as a PDF compressed in an 841 KB RAR archive. The revision letter is not stated in the name, so read the full number on the PCB before trusting it. Apple's 820 numbering identifies a specific logic board design. Once extracted, the PDF lets you search nets and reference designators, follow power rails from the charger through to the CPU supplies, and find which components could load down a shorted rail.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
7-ZipWinRARThe Unarchiver (macOS)