So I got my used iPhone 3GS and it's got a bit of a problem. Every so often it shuts down and wont power back up unless it connected to the USB power cable. It happened 3 times today. I came across 3 possible fixes which involved removing the sim card and other voodoo. I did 2 of them. The third fix involves replacing the battery and I didn't do that. So far no crash and I've run the battery 100% all the way down to 0% playing youtube videos. Anyone ever head of this before? It's a factory unlocked iPhone 3GS on 5.1.1.