My 8310 will boot up and the pin screen flashes for a second and then goes blank - the phone appears to be dead. If i plug in the charger the pin screen comes up again for maybe 5 or 6 seconds but my keypad and roller ball are inactive. It was working perfectly this morning, i powered it off during a meeting and now i cant turn the thing on. If i plug it into my computer I can access files on the phone via the USB cable. But I cant enter my pin to turn it on. I have taken out the battery and reset it and that made no difference. Any suggestions.