I have a Smart Tag 2 that is less than a year old. i got a low battery for the first time. As i changed the battery out the smart tag will not work. with the new battery i got no light or sounds. i have checked the voltage on the battery and it it fine. I went ahead and tried 2 different batteries with the same result. i have tried resetting the tag with no results. i have tried to add it to Smart Things on my phone and it does not show up. it seems dead. I'm pretty sure these are supposed to last more than one battery change.
