If your keyless entry 'fob' still doesn't work after replacing the battery, it might just be a problem with worn out contacts inside the device. These contacts are rubber-like, yet coated with an electricity conducting film that can wear off with use.
A typical keyless entry 'clicker' for your car looks like mine.
By using metallic tape and a hole punch, you can fix it....and the fix works g-r-e-a-t !
metallic tape or (aluminum foil, for which you'll need a tiny amount of glue to make the dots adhere)
a little bit of manual dexterity
Disassemble the device as shown in the pictures.
Using the hole punch, cut out a "dot" of the metallic tape to place over the worn-out contacts inside the 'fob'.
If you cut the dots from aluminum foil, you might want to use tweezers to put the dots in place. I found through trial and error that super glue does NOT work for very long. I happened to have the roll of what I call 'muffler tape' (that's what it looks like to me and I don't rememnber where I bought it, or for what purpose originally)
I just had to repair mine again today after about 9 to 12 months of service. Beats the price they want at the dealer for a new one.
The pictures should tell the story. Good luck.
i just re-did both 'fobs' this morning, June 30, '12, by necessity..the tape dots were coming loose again. This time, to help the metallic tape 'dots' stay in place better I thoroughly cleaned the rubber-vinyl insert to the fob that the tape dots adhere to. Maybe because it's in Florida, (lot of hot weather) or just general use that allows oils from your hands to enter the deveice over time, the insides of both mine had a distinct 'oily' feel to them. So I washed them with soap and water, dried them off, then used rubbing alcohol to finish the cleaning. I also decided to use a pair of tweezers to both separate the paper backing of the tape, and to put the dots in place. In the past I used my fingers to handle the dots and that may have compromised the glue-to surfaces. They seem to more secured now than before.