In many cars, you can simply hold the key fob directly against the start button and press it. There's Usually A Hidden Key InsideA dead battery doesn't just affect starting the car—it can also prevent the doors from unlocking remotely. Fortunately, most modern key fobs contain a physical metal key hidden inside the plastic housing. If you're not sure how your car handles a dead key fob battery, it's worth checking the owner's manual before an emergency happens. And if you've never opened your key fob before, you might be surprised to discover that the "dead" key in your pocket still has one last trick up its sleeve.