stan wrote:
Recently an acquaintance asked us to 'look at' his favourite
microwave. He'd opened it and couldn't find the problem. He felt it
could be the control board!!!!!
My son, also a technician, and I fixed it in about 15 minutes on the
kitchen table; a bad door micro-switch!

I've repaired 5 or 6 microwave ovens and the problem was always a bad
micro switch. Most of the bad switches were caused by a slip on wire
connector making poor contact and getting hot, so I often soldered the
wires to the new switch.