Just wanted to share this. We have a 2002 Toyota Corolla Fielder. It has a key with a button to remotely lock and unlock the car. More than a year ago the remote access stopped working. We thought, Okay probably needs a new battery. Leonie went to Manawatu Toyota where we get our car serviced. The man at the service desk took the key out the back, came back a minute or so later and said the the key was a sealed unit. A replacement would cost NZ$300. I finally decided to have a look at it yesterday and took it apart. Today I went and found a battery for $7 and put it back together; works like new.