If your Gradient does not appear when searching for available units in the app, you may need to have the unit forget its current Wi-Fi network before attempting to reconnect.
Make sure your Gradient is plugged in and powered on.
Using the circular controls on the unit, navigate to the Wi-Fi Network settings by pressing the O button, followed by the gear icon.
Select Forget to remove the existing Wi-Fi network.
Return to the Gradient app and try connecting your unit again.