Archive for Apple logic board 820-4924, revision A, about 2.8 MB in RAR form. The name states nothing else, so model and contents must be checked after extraction; such packages typically hold a schematic PDF, sometimes with a boardview. Apple 820- numbers identify the physical PCB, printed on the board itself. Confirm the number and revision on your board, then use the drawings to trace power rails, locate components and diagnose shorts on the main logic board.
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.