Hi. This is a courtesy call from appliance repair service. Has your refrigerator been running for a long time?
Why, yes it has. Why do you ask?
Well, YOU'D BETTER CHASE IT BECAUSE IT HAS A BIG HEAD START ON YOU! HAHAHAHAHAHA!
And here's another old one: always check everything, even the things you don't suspect.
My problem turned out to be a bad power cord. I've got power cords older than me (thinking about retirement in 10-12 years...) that still work and a 5 year old AC power cord doesn't suddenly go bad in the middle of the night when you haven't moved the refrigerator in a year or so. So I figured since I couldn't find any power at the main control board, it HAD to be serious! I gave up and called a repairman. First thing he did was pull the cord out and test it (in fairness I didn't know the AC was tied directly to a molex-type connector. It just seemed to disappear into sheet metal...). He cut it off, put in a new one with wire nuts, plugged it back in and ...bingo, back in business!
After I paid him the service call fee and he left, I picked up the original AC cord. Right in the middle, hidden by a big piece of blue tape on it from when it was delivered, I see one of the three wires in the molded insulation was completely frayed and destroyed (see attachment). How and when that happened is even more a mystery than how the unit ran until last night or how I missed seeing it. The house is old and where the refrigerator sits, I believe there used to be a gas stove. There's a hole in the floor open to the crawlspace from an old gas pipe. Maybe a rodent came up and ate ONLY the plastic? We have 2 cats, but one is blind and the other is afraid of her shadow...
Oh well, that's $65 more than I should have needed to spend but it's my own stupid fault for not being thorough.