I had my iPhone 3GS with 3.1.2 firmware and corresponding baseband jailbroken and unlocked using blackra1in and blacksn0w. It was working with T-Mobile SIM just fine. I was going to sell the phone and before selling it went into Settings->General->Reset and asked it to delete all data. The phone now won't boot and it is stuck showing apple logo for 2-3 minutes and then then it shows that rotating busy sign as if it is trying to show down but doesn't actually shot down. I can put the phone in DFU mode, but since Apple no longer signs 3.1.2 firmware updates, I am unable to restore to 3.1.2. Any ideas what I can do here? If I could get it into Restore mode (when it shows iTunes logo with USB cable), then maybe I could try to jailbreak it from there again using blackra1n. Please help!