Dead Blackberry Curve 8520

My curve has gone dead don't know how it happened. It wouldn't switch on but when the charger was plugged in the red LED came on and then after a while it would show an battery sign with a red X through. The battery is fine for sure. So, When i take the battery out and put it back in it should boot up right? Well it's not doing, it does nothing. When you connect it to the pc it recognises the phone. I've used the desktop manager and when connecting to the JVM thing it kept on coming up with retry. I've just tried the app loader and delted the vendor file but it comes up with retry too. Stuck on what to do some advice would be helpful cheers guys. It's on ORANGE btw.