Not 100% sure on this, but most ESC's need to be programmed. Power on TX, place throttle stick at high point, connect battery on HBK2, wait for seconds, then bring throttle all the way down. You may hear a confirmation beep or so. If so, then it has most likely taken the throttle programming correctly. I would recommend taking of the blades for this to be on the safe side when you plug the battery on the HBK2. Just make sure the Tx is on when you do this.

Oh, what motor, pinion & ESC are you running?