Ok, so my iPhone 4S (latest version) has been having a lot of problems lately. I got it on Christmas, and everything was fine for a couple of months. Pretty recently, it has been causing trouble. My first problem is that whenever I try to turn it off, it starts back on. I press down the lock button, and I wait until i see the "Slide to turn off" bar, and I slide it. It gets the screen like it's turning off, but after a few seconds of blackness, the apple logo reappears and the phone turns back on. I've tried resetting it and cleaning the charger port with a tooth brush, but nothing works. My second problem is the volume. When I try to listen to music without headphones, it works great for a few minutes then the volume bar disappears. The music is still playing, but I can't hear anything. The volume is totally shut off. When I plug my headphones in, everything works perfectly. What can I do to solve my problems?