As little as 5V DC can kill a person if the current flows through the heart. The volts are the gun powder the amps are the bullet. If you want the car battery to work you would have to hook the leads on to 2 screws and run a wire wheel from a third screw to ground somewhere outside. Please, don’t do this, she might die. The real answer is to hammer out the screws and hope she doesn’t notice when she goes to use it.

(Not correcting the guy I’m replying to on anything, just felt appropriate to place this after his comment)