I have just arrived on holiday. I was using my Xperia U in the car but then stopped for the last part of the journey. When I got out my phone after arriving to take a picture of the view, I found it was switched off, which I had not done, and it had been on 50% battery. When I tried too switch it back on, it got to the second boot screen before rebooting and starting back at the first boot screen. It continued to do this in a cycle, and began to warm up, so I had to take out the battery. When I put it back in, the same thing continued to happen. I have tried charging it, to no avail. What should I do???