An archive of repair files for Lenovo hardware (board NM-E981). Shared as “JT4CA JT4CB NM E981 (REV 1.0).rar” — a .rar file, 30.3 MB.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
7-ZipWinRARThe Unarchiver (macOS)