To change the battery of a Fossil Blue Watch, the user must remove the back case of the watch, remove the old battery by popping open the clip that holds it in place and insert a new battery. The tools required for this operation include a small screwdriver and small pliers.
Fossil Blue Watches come in men's and women's versions. In most cases, they work with a 3V lithium battery. Replacing the battery is a good opportunity to clean the back of the watch. A user can use a small brush to remove any debris from the watch.