Get the correct replacement battery for your Toyota key fob
Locate the small notch or seam on the key fob
Use a flathead screwdriver or coin to gently pry the fob open
Separate the two halves of the key fob
Remove the old battery
Note the battery orientation before removing it
Insert the new battery in the same orientation
Snap the key fob halves back together
Test the buttons to make sure the fob works
Reassemble the emergency key if it was removed