Get the correct replacement battery for your Honda key fob
Locate the seam on the key fob
Use a small 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
Insert the new battery with the correct side facing up
Snap the key fob halves back together
Test the key fob buttons
Replace the battery cover if your model has one