I bought a 16 GB iPhone 3GS (5.1.1) off of Craigslist, and afterwards, I realized it has very weak wifi reception and apparently can't get any GPS signal. Where my other iPhones (2x 3GS) often get 2-3/3 wifi bars, this one can't pick up anything. Standing outside in the open sky, the Maps app spends more than a minute trying to get a fix, and eventually it gave up. When I bought it, it had the iPad baseband on it, so I used Redsn0w to downgrade it to 05.13.04 and then unlocked it with Ultrasn0w. The 3, 4, & 5 serial numbers are 025, so the iPad firmware bricking issue isn't the problem. I searched a bit online and it seems like it's a known issue, but I haven't found any solutions yet. https://discussions.apple.com/thread/2724930?start=45&tstart=0 Any ideas?