The battery for a button is supposed to last for 10 years. But with usage this may vary. You can check if your battery is dead by trying to press the button for a few seconds. If, after releasing, there is no light blinking, you might need to replace the battery.
If you have the tools, you can replace the battery yourself by opening it up with a special torx screwdriver. You will need this because the screws in the buttons have a star pattern. If you need help replacing the batteries, you can contact us for assistance.