A:Answer If you choose to replace the battery yourself, you'll pull on one side of the band and pop the vivofit 3 device out of the band's pocket. Flip the vivofit 3 device over to locate the screw heads. Then you'll need to unscrew 4 small screws with a jewelers Philips screwdriver, remove the cover and swap out the battery. Then reverse your steps (install cover, put the 4 screws back, slip the vivofit 3 device back into the pocket of the band.
You can probably take it to a watch place to have them replace the battery for a small fee.