The battery wires go into the controller and branch to the LCD, so if the voltage goes in, there's not really anything to stop it from coming out unless you shorted one of them and blew it's connection, in which case you should be able to open the controller and solder it back to the PCB, or you can cut the thin red and black wires to the pcb and connect them directly to the battery wires. Alternatively, using your meter on continuity (beep) or resistance, you can measure between the thin and thick red , then the thin and thick black to see which one is broken.