[Fatal_Bert]

Earlier this week my 521 would not unlock. The screen remained black after pressing the power button. I noticed that holding the camera button would make the typical vibration of opening the camera app, but the screen remained black. If I took out the battery and restarted it worked as usual for about 10min (with lock/unlock function) and then would get stuck either unlockable or with a black screen. If it is stuck unlockable, holding the power button still prompts me to slide to power down. So the button is not physically broken, it's a software thing. How could the power button become uncoupled from the lock function?

I factory reset the phone and it cured the problem for 2 days, but it has just reverted. Anybody have any ideas? I can't find anyone experiencing anything similar with this phone. Thanks in advance.

[rdubmu]

I haven't experienced this with my Lumia 920. It sounds like a hardware problem as if it was a software issue it would be more wide spread. Does your phone have any water damage?

If you bought it recently it should be covered under the manufacture warranty.

[Fatal_Bert]

Thanks. It hasn't encountered any water damage that I am aware of. Yes, I believe it is covered under warranty. It is just hard for me to go an extended period with no phone at all. At least for now I can use it if I set the lock screen never to time out--the battery just drains prohibitively fast. It may be hardware-related, but the button physically works and is recognized for the function of turning the phone on/off. Seems odd. I'll likely end up sending it in Monday.

[Fatal_Bert]

Just wanted to leave this with some closure. I factory reset the phone again expecting a temporary fix. I did not restore or import any backed up application data and it has worked fine since. Fingers crossed.

Thanks.