If you were sold a used miner that's not working, especially if you think he is a scammer, I would recommend that you try a working control board to see if that fixes your problem.
Indeed, first determine what the cause of the problem is. Try with another control board, or another PSU from a working S9.
Also, disconnect the Asic boards see if it doesn't reboot, then try connecting one by one only one board at a time, then two.