For them both to die at the same time it has got to be electrical storms or a power surge. You are going to have to pull the logic board on each one and check for burnt or missing traces on the printed circuit.

I'd suspect a problem with the electrical circuit that they are plugged into (reduced voltage). Try running an extension cord to an outlet that you know is good and give it a try.

OK. The problem was fixed a while ago. But I wanted to come back to this thread to put a closure to it so that other people having similar problems may see the resolution.

I ended up replacing logic boards on both units, which fixed the problem. It's a little confusing because the blinking LED (5 times) seemed to indicate a problem with RPM sensor, but since it's completely dead (no light, no motor sound), I reasoned the logic board must be wrong. I ordered 1 board to try it out first - I figured that $70 to troubleshoot the issue may worth it since the service guy I called asked for $80 just to come to look at it, if logic board needs to be replaced, it is $210 per board.

I spent a total of $140 to fix my 2 garage door openers.($70 each, including shipping). BTW, I did spend a little extra and bought 2 LiftMaster Surge Protector 990LM ($25 for 2 include shipping). That should prevent such inconvenience from happening in the future.