intermittent fault with "Sleep Mode" and bezel not closing properly
Rodney, I have the same problem with a 3GS. This was an intermittent fault on my daughters phone. I also noticed that on her phone, the corner (top right - camera area) had a gap between the chrome bezel and the case (back). To put her phone into "Sleep Mode" you had to squeeze the corner tight, and then it would work. So I set out to see if I could fix it (I repair laptops for a living). Well after dismantling the phone I was shocked to find no loose screws in the corner area and also struggled to find out how the bezel has meant to be held down. I decided to glue the bezel. Trouble is the Sleep button will not work at all now and the phone is in a loop as you described. I think the flex is damaged. Or I have not put the phone together correctly?
try loosening the screws securing the sleep button to the bezel. you may have them on too tight and the "on" button is constantly depressed, hence boot loop. I've had this happen in the past and the cable was still fine. The bezel is a really tough part to get on right, personally I'd buy a new back that has the bezel on already...I've tried many adhesives and they are nowhere near as good as whatever Apple used.