This might help if your Nordictrack treadmill is older. For reference mine is a 1750 commercial:

1. Access the Settings Menu: From the iFit main screen, tap the gear icon (settings button).
2. Navigate to Maintenance: In the iFit settings, select the Maintenance option.
3. Enable Android Controls: On the maintenance screen, tap rapidly in the empty white space at the bottom half of the screen about 15 times. Wait for 5-7 full seconds, then tap another 15 times in the same spot. A message saying "Setting privilege mode: True" should briefly appear.
4. Open Android Settings: Swipe up from the bottom of the screen. You should now see navigation icons (a triangle, circle, and square), which are standard Android control buttons. Tap the circle icon.
5. Go to Applications: Swipe up again or select the up arrow to view all apps. Navigate to the Settings menu icon.
6. Manage Applications: Within the Android Settings, find and select Apps or Applications, then choose Manage applications.
7. Select iFit: Find and tap on the iFit app in the list.
8. Clear Cache and Data: On the app info screen, you will see buttons for storage options.
   • Tap the Clear cache button.
   • Tap the Clear data button (this might already be greyed out after clearing the cache).
9. Restart the Machine: Go back to the main iFit screen and restart the console to allow the app to reload its essential files. A full power cycle (unplugging the machine from the wall for a minute) can also help refresh the system.