Hi all, contacted Rad Power Bikes support about this and I'm happy to say it worked! So the problem was our odometer wasn't changing and we had no mph displayed on the screen of our Rad Power Bikes RadWagon.
Steps we took to solve:
1. Remove battery
2. Hold the power (center) button on the PAS selector to fully discharge
3. Unplug the power cable going into the motor
4. Plug motor cable back in (ensure the arrows are lined up)
5. Install battery, turn it on and power up your bike
Hope this helps others who are having the same problem (and saves some time waiting to hear back from Rad support)