Apple boardview for logic board 820-00840, revision A, supplied as a 142 KB zip. Apple assigns 820-xxxxx numbers to its logic boards, and the number is printed on the PCB, so match it exactly before use. The file shows component placement and net connections, letting you locate test points, find which capacitor sits on a shorted rail, or follow a signal across layers. Open it in OpenBoardView, FlexBV or a similar viewer, and pair it with the matching 820-00840 schematic for full context.
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 @cidschematicandboardviewofficial. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.