So, I got my hands on a couple of presence sensors. The first one that I tried refused to pair and I stopped trying after about 10 times. The others paired right away. Hum, so what was the difference between the first and the others. they all reset with button press/hold to reset and green led on for a couple of second and started pairing with brief button press and green led blink on/off once. the only physical difference I can see if that the first one that refused to pair has a little long sticker with a bunch of number on the inside of the coin battery slot and the other have that sticker on the inside of the bottom of the plastic case that the circuit board rests in.
Model numbers for the presence sensors or photos of them?
all 3 look like this: