Apple MacBook Air A1466 material for the J13 platform, J13 being Apple's internal code name for this logic board generation, in a 2.60 MB RAR. No 820 board number appears in the name, so identify the exact board from the PCB silkscreen and compare it with the files inside. Archives of this kind typically carry a schematic or boardview used to trace power rails such as PPBUS and to find shorts. Open it with WinRAR or 7-Zip and check the contents before diagnosing.
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 @hrtechno. 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)