I was trying to upgrade my OS to 4.5 but somewhere along the line the upgrade stopped my blackberry shows only a black screen, the led is blinking twice every few seconds, and when connected to my computer the software says my blackberry has no pin number any help would be greatly appreciated
Disconnect it, pull the battery, replace the battery. If it works, happy days. Probably need to complete the upgrade though. try reconnecting after the battery deal. If your pin still doesn't show, try connecting it without the battery. It should recognize it then, put the battery back in and try to upgrade again.
Stupid statement, but I have to. Your Pearl is on isn't it?
Disconnect your USB, and put it in a different port if possible. Close and reopen DM, when it fully loads, connect your Pearl to the USB, pray.