Hey everyone! I just got an iPhone 3G from eBay in which the seller says the phone has been unlocked, successfully used with T-Mobile, and upgraded to OS 3.1.2. I put my T-Mobile SIM card in but the phone locked and I am not able to slide to unlock or slide to power off. I have soft reset it a couple of times but nothing has worked. Sorry I'm such an iPhone noob, but any help would be amazing!