Boardview archive with a .BRD file labelled only GC2, a 136 KB RAR. The name gives just a project code, likely Quanta's given the BRD naming style, but no brand, board number or revision. Files of this type are opened in OpenBoardView, FlexBV or similar to locate components and test points and follow nets. Because so little is stated, check the layout against the actual board, comparing part positions and markings, before relying on it.
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 @schematicslaptop. 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)