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