My GSM Galaxy Nexus power button also stop working for a couple of days, no matter how many times I pressed it. Finally it works. Here's my solution or non-solution: The first 2 days I keep pressing it out of frustration, taking battery in and out numerous of time. Then I gave up and decided to turn it in for repair. The third day, it started working but differently, each time I short press it, it always ask me restart, instead of just blanking out the screen. It keeps doing that for a day. Then half a day later, it works perfectly again. Short press blanks out or turn on the screen, long press for restart. So the solution is just be patient and praying for others, instead of for the phone.