I had a very similar issue with a Samsung microwave.

It turns out that there are switches engaged by the “hooks” on the door. A dedicated switch for the cooking stuff part. Which had failed.

I was able to get the whole assembly with all new switches off Amazon for like 12 dollars.

Only had to pull the front panel off which meant I didn’t have to dismount from the wall or take the main casing off.

Makes/Models differ so your mileage may vary.

Edit: found this: https://youtu.be/czZHdMB5eEU

Repair clinic videos are amazing and the site will help you find the parts. Which I promptly look up on Amazon for fast shipping and cheaper price ;)

I confirmed the door switch was dead by opening up and removing it and you could feel that the switch was flat/floppy.