自己解決
故障ではないらしい

米Amazonで買ったんだけどやっぱレビューは低評価を読むべきだなーと
返品することにしたよ

too slow

Take way too long to connect every time and reads aprox 4 degrees higher than it should... case in point, waste of money.

It is super slow! It takes forever to connect and after it connects, it takes forever to show the temperature.
You can never tell if this thing is working or not, no LEDs no nothing to show the status.
The only way to see if it is working is if you have a Garmin watch with the proper app installed and it only works with a few Garmin models.
Lately it has been eating the batteries.