Archive for Apple logic board 820-2610, about 4.25 MB in zip form. The name states only the board number, not the Mac model or the board revision, so the contents need checking after extraction. Packages named by 820 number usually carry a schematic, often in PDF, and sometimes a boardview for an OpenBoardView-type viewer. Technicians use them to trace power rails, find test points and work through no-power or short-circuit faults. Confirm that the 820 number printed on the board matches before you start.
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 @notebookschematic. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.