Found articles from others on the internet, which gave the link for www.appliancepartspros.com.
1. Turn off breaker / power to microwave
2. No need to dismount the unit.
3. On the top front of unit (looking down on top) remove phillips screws
4. Slide piece above the door to the left and gently pull it out/off and set aside
5. On the plastic cover at the right side of the door, remove 1 screw (top left)
6. Slide the piece (with buttons) up and gently pull it out/off to reveal components.
7. For your peace, take a photo of the wire connections with a smart phone. They are color keyed and of a specific size connector.
8. Squeeze the connectors to release and pull off all connectors/cable
9. Clean hands please! Remove 3 screws holding circuit board and lift up and slide out.
10. Remove medal box that houses the circuit board. Plastic tabs hold the box in place
a. Use a case knife to gently pry box sides off tabs and pull up/off each of 4 tabs.
b. Remove medal box.
11. Remove the (square) button unit by gently prying up and pushing off of plastic holding tabs
12. Remove the circuit board (same as 11 above) to access the buttons. Observe rotation
13. Install new button unit, clear plastic sheet, circuit board and button housing.
14. Reassemble.