Try booting into safe mode and see if you have any luck.
Quick Tip: Boot Motorola Droid Into Safe Mode | Droid Life: A Motorola Droid Blog
I'd say if you can't even get into safe mode after applying the update, something serious happened; and you'll most likely have to flash the phone back to factory defaults with a .sbf file and RSD Lite.
Quick Tip: Boot Motorola Droid Into Safe Mode | Droid Life: A Motorola Droid Blog
I'd say if you can't even get into safe mode after applying the update, something serious happened; and you'll most likely have to flash the phone back to factory defaults with a .sbf file and RSD Lite.