I have had my n810 for about 2 weeks and am perfectly happy with it, until today. I was updating a few apps when all of the sudden I hear "click click" (as if i had just hit the power button) and then it turned off. Before I could turn it back on, the nokia logo popped up and it started booting itself. After it started back up, I was able to use it for a few seconds and then the "click click" and it turned off again. Not knowing what else to do, I backed everything up and reflashed it. After restoring everything, I still got the same issues so I reflashed again and used a older backup. Still no good. So I reflashed again with no backup, and it appears the reboot loops have stopped and I can at least work with it, only now neither the power or hold buttons work. Pressing the power doesn't pop up the menu and I can only turn off the device by holding the power for a full minute. As for the hold button, it acts really weired, and will lock the device (without showing the popup in the upper right) but will not unlock, but if i open the keyboard, the screen unlock appears. I'm sure its not a problem with the root image (I have flashed it before without issue)

Any ideas?

EDIT: Okay, I took the battery out for about an hour and now the power button works again, but the hold button still doesn't work.

EDIT: It was a hardware problem. After sending it back to Nokia (twice, they didn't fix it the first time) I finally got it repaired.