When your Toyota remote quits working because the battery in it is dead, it is fairly simple to change the battery and have your remote working just like new. Some Toyota dealers may provide this service for free. If not, or you prefer to do it yourself, all it takes is a couple of small tools, a new battery and some patience.
Turn your remote over so that the Toyota symbol is facing up. If you look along the top edge of the remote you will see a small "crack" in the plastic about a 1/4 of an inch below the top of the remote. The crack runs all the way around that side of the remote. That crack is actually where the piece of plastic you are going to remove slides onto the remote. Just look to see where the crack goes so you have some idea of what is going to be removed from the remote.
Look at the bottom of your remote to see if it has a lever. If it has a lever, slide it and a small key will come out of the remote so you can open the door even when the remote is not working. Use the lever to remove the key. Keep in mind that when you are removing the plastic piece referred to in step one, as you slide it off you will have to move this lever as if you were removing your key to fully release the plastic piece.
Stick the flathead screwdriver or small pry tool gently into the crack located at the top of your remote and as you slide the lever push in a downward direction. You are not trying to pull the plastic piece off the remote, but rather you are sliding it off the remote. If you are releasing the lever, the piece of plastic should slide off. You should see four small Phillips head screws once the plastic piece has been removed.
Remove the screws and remove the plastic cover over the battery. Either on the piece of plastic covering the battery or on the battery itself it will state what size the battery is. Replace the battery with one of the same size. The (+) side should face up. The battery will state on it which side is the (+) side.
Replace the piece of plastic that covers the battery and check to make sure the remote works before you put the screws back in. If the remote does not work correctly make sure that you have properly inserted the battery with the (+) side up and that it is sitting flat inside the remote. If it still does not work properly, check to make sure the connectors do not have corrosion on them. If the connectors have corrosion you will generally see a white powdery substance on the battery you removed or the connections underneath. If you see this, remove it with a little rubbing alcohol on a small cloth or cotton ball being careful not to get your remote wet. Once you are certain the remote is working properly you can put it back together.
Replace the screws and then slide the outside plastic piece that you removed back onto the remote making certain you have clicked it firmly into place. As you are sliding it back onto the remote, you will once again have to move the plastic lever to get the plastic piece all the way back on.
If you do not have a screwdriver small enough for the job, they are inexpensive and you can likely pick one up at the same place you purchase your battery.