guys, everyone please help me to find out this problem, i had bought a iphone 4 GSM from ebay, and suddenly this phone lost signal (2 day after i purchased it). I had backup before, and restore when the phone became trouble. But, why my phone often lost signal? is there software or hardware issues? if my phone lost signal, when i was restarting, the phone gone in to just boot (stuck apple logo). please help me guys, thanks a lot