It appears that the screens may be unresponsive at this time so try putting the device into the charging cradle and then press/hold both side buttons for at least 10 seconds to complete a Factory Reset.
If the Factory Reset was successful, there should be a Fitbit logo on the device screen and a message to download the app. At that point, check your phone to see if the Inspire 3 is Bluetooth paired and then unpair it if it is. Finally, uninstall the app, restart the phone, reinstall the app, and then complete the setup process again.
