To replace the battery, use a small Philips screwdriver to loosen the screw and detach the battery compartment cover. Next remove the old battery and safely dispose. Then insert a new CR2032 battery ensuring the positive side faces outwards, then put the battery cover back on and tighten up the screw. DO NOT OVERTIGHTEN THE SCREW. There will be a beep after a few seconds and using your iPhone nearby, check your item is available again on the Find My App.