My iphone was working fine...had 33% battery power left. All of a sudden the phone would not turn on. Blank screen. If you ring it...you can hear it ringining from another phone, but from the Iphone 4- u press sleep button- again and again..you cant disconnect the call or even answer...the Iphone 4 is still blank. Any advice before i go to the apple store? Inside i have a pay as you go sim. Its NOT jailbroken. Iphone 4 is unlocked from Apple store.