Replacing AirTag battery
December 13, 2023
AirTags use CR2023 batteries and some manufacturers put on bitterant to prevent children nibbling on it. This bitterant is usually nothing significant to electronics, but apparently enough to prevent contact for AirTags.
The outlined gray-ish on the back (left) is the bitterant mentioned earlier. Rub isopropyl alcohol using cotton swab until it fades away (right), then try again.
A successful battery installation would ring the AirTag chime upon closing the cover.