Microwave will not start at all; display is on and accepts input, but pressing Start does nothing.

Safety First: Unplug the microwave before accessing internal components.

• Check door indication: Many JennAir models show a door icon or message if the door is not detected as closed. Open and close the door firmly and see if the indicator changes.
• Test keypad: Try other functions (Timer, Clock). If some buttons do not respond, the membrane keypad may be failing.
• Inspect door switches: Remove the control panel and inner trim to access the door switch assembly. Test each switch with a multimeter for proper continuity when the door is closed.
• Check latch alignment: Ensure the plastic latch hooks on the door engage the switch levers fully. Replace the door latch assembly or adjust the switch bracket if misaligned.
• Control board: If switches and keypad are good, the control board start relay or logic may be defective and require replacement.