It sounds like the oven may have lost it's power (L1 connection) or neutral at the terminal block (AP2929061) which is located under the top panel. Several wires attach here, but then go to the various connections inside the oven and microwave. The connection for the microwave light is different than the one for the control board which is why it still illuminates. You can get a peak at it by removing the front control panel and see if you find a loose wire (turn off the power first), or pull the entire unit out of the cabinet and remove the top. But I would look for a loose or burnt wire.