Here are all tools that you might need for a successful battery replacement. Not all of them are necessary, but some of them are must. Must have tools are:

Small phillips head screwdriver (mine is from the older iFixit kit, Tweezers 2 pairs (metal for screws and plastic for battery handling), Silicon grease for the gasket (I have one with easy applicator, available at your favorite online store)

Optional tools are nice to have, but if you don’t have them there is no need to buy them:

Watch strap removal tool (mine is Bergeon 6767), Watchmaker’s loupe, Watch wise, Finger cots

Of course, new battery is also required. Type used by this movement is CR1220

I started by removing the strap with the strap removal tool and shroud by unscrewing 6 phillips head screws on the side of the watch. The watch was full of gunk from the wearing it so I washed it with dishwasher soap and warm water first.

The next step is to unscrew 4 phillips head screws on the back of the watch.