Yes, that generally means there is a short. You want to disconnect the cable at the head on the roof and measure the voltage there. It must be a solid 12+VDC. If the lamp goes out when the cable is disconnected from the head, the cable or the power supply has a short. If the power stays on and reads good voltage while disconnected but the light goes out when you plug it into the head, the head has a short and that needs to be replaced.