Fiat 2013 500 ABARTH Owner's Manual page 20

18 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE
2. Rotate the screw located on the side of the Key Fob
using a small screwdriver.
Key Fob Screw Location
3. Take out the battery case. Remove and replace the
battery observing its polarity.
Battery Case Removed
4. Refit the battery case inside the Key Fob and turn the
screw to lock it into place.