Apple 820-4924 boardview, revision A, as a 576 KB .brd file, the same size as a separate copy labelled new. It maps every component and net on the logic board, letting you click a rail to see all connected parts, locate test pads and find components described in the schematic. Open it with OpenBoardView or FlexBV. If one copy shows missing nets or loads incorrectly, try the other, and check the 820 number and revision on your PCB first.
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 @one5technology. Enginerys does not host this file.
How to open a .brd file
The most common boardview extension. Several unrelated formats share it, which is why one viewer opens a .brd and another refuses it.