1. Locate the key fob's battery cover. It is usually a small, plastic cover located on the back or side of the key fob.
2. Use a small, flat-head screwdriver or your fingernail to pry open the battery cover.
3. Remove the old battery from the key fob.
4. Clean the battery contacts in the key fob with a cotton swab or tissue.
5. Insert the new battery into the key fob with the positive (+) side facing up.
6. Replace the battery cover and press it firmly into place.
7. Test the key fob to ensure that it is working properly.
Here are some additional tips for changing the battery in a Lexus LS430 key fob:
* Use a CR-2032 3-volt lithium battery for best results.
* Be careful not to damage the battery contacts when prying open the battery cover.
* If the battery cover is difficult to remove, try using a hair dryer or heat gun to warm up the adhesive.
* If the key fob is still not working properly after changing the battery, you may need to have it reprogrammed by a Lexus dealer or a professional locksmith.