How do you unlock a keyless entry car with no key if the battery is dead?

To unlock a keyless entry car with a dead battery, you can check for a physical key hidden within the key fob, which can often be used in the driver's door lock. If your car has a manual keyhole, insert the key to unlock the door. Alternatively, you can jump-start the car’s battery or use a portable battery booster to power the key fob and unlock the doors. If these methods are not viable, contacting a locksmith or your car's manufacturer for assistance may be necessary.