One of my AirTags no longer connects to phone, other 3 work fine- beyond warrantee

One AirTag no longer connects to phone yet 3 other tags bought at same time perform flawlessly. I have replaced battery. I brushed out the receptable with a soft static free brush. It is not a battery with a child protective coating on it. I have attempted to reset with taking battery in and out 5 times, listening for the chirp to change on the 5th (or even the 6th insertion) and, interestingly, IT IS THE SAME CHIRP however many times battery is inserted. The phone sees the AirTag and asks about what to name it, I select a name, I agree to terms then get a message: " Cannot Connect to AirTag, Make sure Buetooth is turned on and AirTag is in range." I have toggled on and off Blue Tooth, Wifi. The other 3 AirTags, purchased at same time as this fourth Tag perform flawlessly. I took it to Best Buy Apple Genius bar as recommended by Apple Support. The guy at their Geek Squad knew less than I did. I am wondering if there is anything an Apple Store genius bar might do, or see in the AirTag with a physical inspection before "last rites" are said?? I know it is just $25-$30 for a new one- just wanting to exhaust all possibilities.