Type-C firmware for the ThinkPad X280 on LCFC board NM-B521 revision 1, marked tested. At only 104 KB this is not a main BIOS image but most likely the firmware for the USB Type-C or PD controller chip, often reflashed when charging or Type-C ports stop working. LCFC numbers Lenovo boards in this NM format. Identify the exact small flash chip on your board, read and back it up first, and confirm the image matches its capacity.
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 @generalbios. 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.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →