The problem can be a bad door lock switches as well as a bad oven control board. You may want to check the switches, the door lock motor and their wires first. If there is nothing wrong, replace the control board.
- The door latch assembly (lower oven)
Part number: AP4094734 
- The control board
Part number: AP4396791 
Here is the
Service manual.
Here are the breakdown diagrams and
Replacement parts for MAYTAG MER6772BAB Freestanding - Double Oven - Electric | AppliancePartsPros.com
Gene.