update: door is closed and won't open. read other posts so I checked the stop nut but it's 3-4 inches away from that.

Another post noted that 5 blinks was "Possible RPM sensor failure/Motor Overheated - unplug to reset." I have unplugged for an hour and plugged back in - still nothing. What is RPM sensor? is it a DIY fix?

It's not the RPM sensor. When that goes bad the motor will always run for a few seconds. You need to start by undoing whatever it was you did before it stopped. No matter how silly it sounds although replacing bulbs doesn't normally cause the opener to quit. I would remove the cover and look for loose wires and check the logic board for bad solder connections on the PC board. Be sure to unplug the unit first.

Thanks don_1 but still no go. One original bulb was broken so I couldn't replace it. Pulled the cover and logic board looks fine - no loose connections or bad connections that I can see. No burnt spots either.

Replace circuit board or replace the entire unit?

Update: unit has 2 logic boards - pulled them both out. One board has ic's etc and looks fine...other one has transformer etc and has a burnt spotnear where one of the power leads connects (I think). solder connections look fine and nothing's loose. Replace the board?

If it has 2 boards it may be an older model. Parts might not be available. Go to Sears parts and check. You will need the model number which starts with 139.