With the ring put in place, take the new replacement battery and set it at its position in the key fob. The positive (+) side should be up, facing you. Return the battery cover to where it should be, then reattach both sides of the key fob case. Press until you hear them click into place.

Here are the steps to learn how to change battery in mazda key fob: Remove the battery cap and put it near the key fob for safe keeping. Now that the battery is exposed, remove the old batteries. Be careful not to damage the rubber ring under the battery. If it is damaged, you’ll need to replace it as well.