How can I fix a Droid Razr Maxx's power button? Suddenly, today, the power button stopped working.  I tried to turn off the screen and it wouldn't.  Everything else works just fine.  Eventually the screen timed out, and wouldn't turn back on.  Plugging it into a charger turns the screen back on, but that's fairly useless away from power...

I had heard that soft reset (power button+volume down) fixes it, but not even that worked.  It would only register it as volume down.  I plugged it into adb and rebooted it that way, to no avail.
What can I do?
The power button is handled at a very low level by something like a watchdog, so if it's not working, the problem is probably in hardware, not software. That means it probably needs physically replacing. Take it to a repair shop and have them check it out.

Even if you don't think you did anything to break it, it could be the result of an earlier impact: e.g. it cracked the circuit board, but only after continued use has the crack broken the electrical circuit.