Whirlpool Duet

My washer locks when you start it, but it won’t start the wash cycle. Sometimes it starts to fill up with water, sometimes not. It never spins, and you have to manually unlock it. I ran the diagnostic test, which yielded no result I could understand. The wash light came on- no blinking, and stayed on. We tried replacing the Control Panel (CCU), but that didn’t fix it. We were told it may be the motor drive (MCU), but I hate to dish out another $200 for something that may or may not fix it. Please help!