It can happen to anyone once in a while that you get a model that doesn't work. Have you received a replacement device in the meantime? Does everything now work as expected?

I have now had two Backbeat FITs (the model has been around for four years or so). Both had the same fault as described here - unfortunately there are countless cases documented on the web. I was able to replace the first one under warranty, but with the second one, the fault occurred well after the warranty period and was not replaced. Definitely not a "Monday model" with this fault!