my Iphone 3Gs has been on charge for a while now, I believe it is bran new and I have changed the charging devices but it wont seem to turn on it just is appearing with the spple symbol & then I'll hold the on button on and it will go to unlock screen for less than a second and then loading on a black screen then back to black screen then to apple symbol and repeat. it is making the sound over and over aswell. Its been doing this for a few hours.. HEEELLLPP!!!!!!