Ducati Diavel Workshop Manual page 263

The Hands Free system
Remove the battery (2) from the printed circuit board (1) and replace it with a new one.
Pay attention to polarity: the positive pole (+) must face upward.
Important
Use only batteries of the recommended type (CR 2032).
Reinsert the printed circuit board (1) from the side with the battery (2) into the plastic shell.
Apply slight pressure on the antenna (3) of the printed circuit board until you hear a click.
Align the two shells of the grip and press on the area indicated by the arrows to close them.
Make sure that you hear a "click" upon closing and that the key is well closed.