My door opener went completely dead and would not supply power to the lights. I check outlet for power and had 120V. I thought the logic board was fried, so I bought a used motor module off ebay (cheaper than a replacement logic board). I removed defective unit and replaced w/ used unit w/o problems. Unit now works fine.

I decided to check my removed motor module by plugging into power and shorting the manual switch to see what would happen. It came on (LED flashed code 1) and when switch was shorted ran a few seconds and went off. Motor stuttered and LED flashed code 4 when I shorted again to see if motor would reverse.

Is it possible, the logic board is OK? Can I test the logic board w/o the saftey sensors attached to logic board? I will keep removed motor module for spare parts, but I have sneaky suspicion that it's OK.

thanks