Some jewelers charge as much as $30 to change the battery in your Casio watch. With a little careful effort you can save both money and time. This process can be difficult, and should be undertaken in a clean, quiet environment where you can pay close attention to the task at hand.
Remove Old Battery
Spread the towel out on a flat surface.
Remove the watchband if necessary in order to access the back of the watch.
Unscrew the back protector from the watch using the correct size miniature screw driver. Place the screws in a small pile on the towel. Be careful not to drop them; they are difficult to find.
Remove the back plate by unscrewing the small screws. There is a tiny spring on the underneath of the back plate. It may be visible, or not. Make sure not to turn the watch upside down or the spring will dislodge.
Remove the rubber protector to find the battery.
Use sharp point tweezers to remove the clasp covering the battery. There is a small hole at one end of the clasp. Insert one end of the tweezers into the hole to spring the clasp loose.
Remove the old battery with tweezers.
Insert New Battery and Reassemble Watch
Pick up the new battery using regular tweezers and put it into place. Do not touch the battery with your fingers.
Replace the clasp over the top of the new battery.
Perform a reset by touching the AC contact with one part of the tweezers, and the back of the battery with the other part. Hold for a few seconds. Lift watch carefully and look up at the front to make sure the watch is working. Do not turn the watch over.
Replace the rubber cover.
Replace the back plate by screwing the small screws back into place.
Replace the back protector by screwing the small screws back into place.
Reattach the watch band to the watch face.
Use a small towel to place the screws on so they don't become lost.
Do not turn the watch upside down once the back plate has been removed. The tiny spring may fall out and is very difficult to replace. Do not touch the new watch battery with your fingers; use tweezers to put it into place.