Have you tried a M115: Get Firmware Version and Capabilities ?
See if tells you anything.
If you cant find the board specs uploading new firmware is never going to work... you will need to trace every IO pin and work out what pin is connected to what device.
See if tells you anything.
If you cant find the board specs uploading new firmware is never going to work... you will need to trace every IO pin and work out what pin is connected to what device.