Step 1. Using a small screwdriver undo the four screws in the corners of the watch back and put them somewhere safe.

Step 2. Once all the screws are undone, remove the back plate.

Step 3. This particular watch has a plastic cover which can be simply lifted off and put to one side.

Step 4. In this watch the battery is held in position with a clip.

Step 5. To release this clip you need to push the point of a very small bladed screwdriver or a pin into the hole as shown.

Step 6. Push the clip away from the battery so that it lifts over the retaining lip.

Step 7.The clip is undone here, you can now remove the old battery.

Step 8. Gently ease the old battery out from under the clip using a small screwdriver or other pointed tool.

Step 9. Replace with a new battery. When fitting the new battery try to avoid touching the battery surfaces with your hands as grease and dirt from your hands can reduce the battery life. Plastic tweezers are useful for this step.

Step 10. Push the clip back into position. It will clip over the retaining lip and hold the battery in place.

Step 11. Replace the plastic cover.

Step 12. Screw the back plate back in place.