Press the hand controller throttle all the way down for up to 5 seconds until the LED lights begin to flash. If nothing happens, make sure the hand controller is fully charged.
To charge the hand controller, check that the inductive charging plate is active and the center of the hand controller is correctly positioned in the center of the charger. The center of the hand controller is located between LED lights 4 and 5. It can be a little sensitive so try moving it around if at first it does not react.
As the hand controller is charging, the LED lights will begin to flash one by one reflecting the progress. When the first LED light flashes the hand controller battery is 20% charged, when the second LED light flashes it's 40% charged etc. When it's fully charged all the lights go out.