To recover, you could remove the memory card and update again. After the update the device should reboot and work correctly.
Note: Removing a memory card before the update only helps in cases when the software update (via SW Update) seems to be working normally, for example when the software is correctly downloaded to the device and an installation note appears on the screen. After you press OK, the device starts to reboot but it never ends. You need to take off the battery and place it back again to reboot your device. The device software is not updated.: