I was tired of GPS not working on my iPhone 3g with 4.2.1 and the ipad base band 06.15.00 so it could be used on TMO, so I picked up a 3g on craigslist that was unlocked and jailbroke. This 3g has 4.2.1 and 05.11.07 base band. The guy who sold it to me assured me GPS worked fine, but it doesn't. It will only triangulate wifi and cell towers and never finds a GPS signal when I try the skobbler GPS app with wifi turned off. Is there a way to fix GPS without restoring the firmware? Sorry if this is a NOOB question, but I've read for hours and can't find a straight answer. Should I downgrade the firmware to 3.1.2? If so, can I use the official 3.1.2 firmware and unlock/jailbreak with Blackra1n, or do I need to create a custom firmware to downgrade? Thanks for any advise.