Remove vent cover then remove touch screen control panel. When you remove control panel take photo of where everything is plugged in then unplug and remove control panel. 3 door switches located next to door in a plastic chassis. Test each switch with current tester. Remove the bad switch and replace with the new one. You tube DIY helped.
The diagnosis is about an hour. Coz, I need to open the control panel, got a tester, and trsted all critical parts inside the panel. Also, replaced the fuse just to make sure its a new one. Found out it was a switch (bottom part) that control the open/close of the microwave door.
When found out the problem, the rest of the work is easy.