Maytag dishwasher starts, fills, then quits

Our 15 year old Maytag dishwasher starts, fills, then quits. Motor does not start. I installed a circuit board out of an identical unit, but that didn’t change anything.
Is there a diagnostic mode for this unit? any suggestions of what could cause this? My wife really likes this dishwasher, and hates to think about replacing it.

Thanks,
Bill