I just bought a used 3GS off ebay for my 9-year-old daughter to use as a glorified iPod touch. I had a stock 3GS for her but its battery began to swell, so it's not safe to use. I bought the device knowing it was jailbroken, but was unaware that it had been unlocked to operate on T-Mobile, as evidenced by the T-Mobile SIM card it shipped with. Here's what I'm experiencing: The phone fires up just fine, holds a charge, and walks thorough setup up until it needs to be activated. Trying to activate through iTunes results in a "There is no SIM card installed in the iPhone you are attempting to activate." error. Trying to activate over WiFi results in the Phone being unable to find an authentication server. I replaced the T-Mobile SIM with the AT&T SIM from my previous 3GS, but the errors continue. I've reached out to the seller to try to uncover exactly what was done to the phone, but haven't heard anything back yet. What steps do I need to take to get this phone to a state where I can have iTunes to a factory reset?