RAR archive of 1.82 MB for Apple board 820-2330. The name carries only the board number, with no revision, project code or list of contents, so open it to check whether a schematic, boardview or both are inside. Apple uses 820-xxxx numbers for its board part numbers, printed on the PCB itself. Match that number and the revision before working, then use the material to trace rails, read the power-on sequence and narrow down shorts or missing voltages.
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 @Mac_Shematic_Santale. 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)