My iphone 4 won't turn on - 4

My iphone 4 simply won't turn on. Its running on 5.01 and has the gevey simcard plus jailbroken. I have tomobile as my network hence the gevey sim card. It was working all fine but it simply won't turn on anymore. When people send imessages it says dilvered but the phone seems to be off. I connected it to the computer and the computer recognizes it and everything but just won't turn on.

My iPod touch was doing something similar. When I plugged headphones in, it would turn off and the screen would go blank. What I did was I held down the lock button and home button at the same time for ten seconds. I don't know if its the same thing though. Hope this helps.