It's possible to change an Invicta watch battery without a tool. All that's needed is a lint-free cloth and a new watch battery. A tiny screwdriver and tweezers are both optional.
Lay the Invicta watch on its face on the lint-free cloth to keep the watch from being scratched. Next, rotate the back case cover with your fingers counter-clockwise to loosen it. Remove the back cover completely from the back of the watch. Gently pick up the rubber gasket and set it aside. The rubber gasket is the rubber piece that's directly underneath the back cover of the Invicta watch. Insert a fingernail--or a tiny screwdriver--underneath the battery, and pry it out of the battery compartment. The battery is usually underneath a small clip or strap that secures it in the battery compartment. Move the strap or clip out of the way before removing the battery. Use a fingernail or a tweezers to put the new Invicta battery into its holder. Be sure the strap or clip is out of the way first. Make sure the new battery is in the same direction the old battery was in. Replace the rubber gasket. Then replace the back cover of the watch onto the watch.