By pure chance I tapped the thermistor (large black circular part marked AS32 that resists power surges and protects the unit) and the lights reappeared. I had previously ordered this part through Amazon in 2023 after I deduced that this must be the problem but suspect my soldering attempt did not work out well. Fortunately I ordered 2 thermistors and will solder in a replacement and hope this works out. We had a lightening storm yesterday and this may have been the source of a surge.