We get many inquiries where the car owner can't start the car after changing the battery.
If your key does not work after you change the car battery, start the engine by pressing the START button with the keyfob.
If your key does not work after changing the key fob battery, here are some possible causes.
Don't touch the key fob circuit.
Avoid touching the key fob circuit with your bare hands.
Either handle the key fob circuit and electronic terminals with care or use gloves to change the remote battery.
Handle the key fob circuit with care
When changing a key fob battery, handle the circuit inside the key fob with care. Also, when opening the key case, be careful not to damage the key.
If your car manual asks that you use a flat screwdriver, follow that recommendation. If you decide to use other objects to open up the case, you may damage the housing.
Hold battery by the edges.
If you hold the battery by pressing your fingers on the two flat surfaces, you can shorten the battery life.
Holding the battery this way can seriously deplete the battery capacity.
Note the battery positive (+) orientation.
You may have installed the battery the wrong way. Try flipping it upside down. Before you remove the battery notice, it's orientation. Is the positive (+) facing the back case, or is it facing you?
Note that only the (+) side of the battery is typically marked. The negative (-) side is not marked on most batteries.
Use the correct battery type.
Suppose your remote uses CR2025. Don't try to fit the wrong battery in the shell. Make sure to check with your owners manual the size of the battery and install the correct size.
What's even worse is that you may end up installing a battery that has the wrong voltage and can end up ruining your expensive remote.
Damaged key fob shell
If you can start the car but can't lock or unlock it, the problem may be the buttons. If the buttons on your remote are worn out, consider replacing the key fob shell instead of the key.
Replacement shells typically cost around $20-$35. A new key can cost over $300 depending on the make and model.