Sony VAIO firmware image for the MBX-253 motherboard, with the Z40BR tag also given in the name, packed as a 979 KB RAR archive. MBX is Sony's internal board numbering, so the code printed on the PCB is what decides compatibility, not the retail model. A dump like this is written to the BIOS SPI flash with an external programmer when a board stays dead or loops after a failed update. Read and keep the original chip contents first, and confirm the extracted image size equals the chip capacity before programming.
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 @biosarchive. 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 →