Intermittent Power within device

[GregB10]

Mother-in-laws garage door opener works fine until there is a break in power (power outage, or unplug). With power to the unit, it takes a month, or longer before the circuit board LED's light back up, and opener functions again.
Have cleaned all connections, and even re-flowed solder joints. Can't see any perceptible capacitor swelling.
I'm sure it's something simple. Would rather repair than replace entire PCB.  Thanks!

[Kim Christensen]

Does it have a wired switch in the garage?
If so, is this button also affected by the the 1 month delay, or is it just the remote?