Make sure the hand controller is fully charged, if you need help with that see https://support.radinn.com/hc/en-us/articles/4417006670228-Charging-the-hand-controller
Check that your hand controller has the latest Firmware. To update, open the app and find the section "Hand controller" at the bottom of the home screen. Hold the throttle of the hand controller down for around 45 seconds until the LED lights stop flashing and LED lights 2 and 4 come on with steady lights. Let go of the throttle and click on Update Hand Controller in the app. If you need help submit a support request and we'll assist you.
To pair the hand controller with the board, attach the magnet key to its designated area at the back of the board. Press the hand controller throttle all the way down until the LED lights begin to flash. When they stop flashing, the hand controller is paired with the board.