Well, hopefully by now your device has finished updating. The speed of the Internet through your Wi-Fi modem can sometimes extend the new firmware downloading in more than the typical expected time, although 20-minutes is very abnormal and your device is 'hanging up.'
If you were not successful completing the firmware updating, now I would repeat the setup, but I would not restart doing the typical regular setup. Your initial attempt may have downloaded some slightly corrupted firmware that caused your device to 'hang up' during the lengthy setup. Now instead, you want to 'clean that out' any potentially corrupted firmware software and restore your device back to the way it came from the factory but utilizing a Factory "Hard" reset (press and HOLD the reset button down for about 30-seconds before you release it). Then complete the device setup by following the instructions. When you get to the part where you have the option to "SKIP" the setup, do not! Wait until your App steps to the next setup page on its own, even if you audibly hear her announce that your device is ready. You want to avoid interrupting the firmware downloading to insure you get a nice clean firmware.
If you still encounter difficulties setting up your device, telephone Ring Support for help: