Slide the flat end of a spudger under the edge of the battery where the vibration motor was.

Pry up the battery until you can grip it with your fingers.

The battery is held in place by mild adhesive. If you're struggling to pry up the battery, apply a heated iOpener to the bottom of the watch for about 2 minutes to loosen the adhesive. Don't apply the iOpener directly to the battery.

Don't try to remove the battery all the way yet, as it‘s still connected to the watch assembly by a delicate cable.