I just got back from Glastonbury festival and on Friday morning my phone ran out of battery. When charging a red blinking light was displayed. I read that it needed more charging and when it stop blinking I turned it on and it appeared fine. In the 1st 30 second of it loading up I can put in my pin and access the phone fine but as soon as I open an app or something the phone locks again. The service bars are also empty(which is worrying) and the wifi works fine(get fb notifications & emails which i can't access). After that as soon as I put my pin in and press enter the phone locks itself again. I know it's locking as it does the locking animation.
I haven't been able to find any problems similar to this. Any ideas?