Boardview for a motherboard numbered 12127-1, a pattern used by Wistron, the ODM that builds boards for Dell, Acer, HP and others. The name gives no laptop model, so match the number printed on the PCB before trusting it. A .brd boardview opens in tools such as OpenBoardView, FlexBV or BoardViewer and lets you locate components, follow nets between parts, find test points and check for shorts on power rails. At 41.4 MB it is a large, detailed layout file.
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 @ShareMan_Electronic_Files. 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.