mAY BE THE LITTLE METAL THINGY INSIDE OF THE CONTROLLER, ON THE KNOB USED TO TURN THE TANK. SOMETIMES HENG LONG CONTROLLERS GO OUT FAST, U MAY WANT TO JUST GO TO www.hobbypartz.com to get a new heng long controller, its like 8 bucks pluse u get a new battery and charger and so on, just use the frequency chip that is still in your old controller and put it in the new one if you get it. that's what i did.