i have an iphone 3Gs IOS 4.1 and today it turned itself off it had 40% battery left. it wont turn on it just sits there with the apple on the screen and vibrates every 10-15 seconds. i have tried doing a hard reset but it still loads back to the apple and vibrating. wall charger wont change it. plugging it in to my computer crashes my itunes. but the last time i plugged it in it told me i had no sim card. i dont know what else to try can any one please help!!!!