When the controller clicks like that the problem is usually with the battery. A bad battery can become fully charged, however, when a load is applied it can drop Voltage to the point that the controller will go into Low Voltage Protection (LVP) mode. The LVP of the Avigo Extreme controller should be around 10.5 Volts.
You could check the battery Voltage with the power switch on and throttle at the full position to see if it is at or below 10.5 Volts to confirm its condition.
Joshua yancey