My cousin tried to jailbreak my iPhone 3GS for me a few days ago; while he was in the process, the iPhone shut off by itself. And when he tried to turn it on, it wouldn't turn on. After putting it into charge, the screen would show up with the color yellow for about 15 minutes, and then go to the normal black screen with the white apple in the middle for about 10 more minutes before shutting off on its own and repeating the yellow screen/apple screen cycle again. Other times when I put it into charge it just stays at the black screen with the white apple in the middle; it just stays there until I ultimately give up and turn the iPhone back off by clicking the home/lock button together. Without in charge, when I try to turn on the iPhone, the screen turns a dim black color, noticeably seen, before going back to the normal "off" screen. I really don't know what to do; I've tried the holding home/lock button for a number of seconds, holding home button with iTunes open; none of it works. I really need help, since I really do not want to go to the store and pay over a hundred dollars to fix it. Thanks!