watch bubble popped.

I had a bubble form on my watch band and I believe this is the 4th replacement.  Because they don't have any Vivosmart 4 left in stock they refuse to exchange it.  The last time they sent me a replacement I asked the rep, "what happens when you stop making this watch"  and he replied that "they redesigned it so the battery bubble won't form."  They offered a %30 discount on a new watch but that just doesn't seem logical. 

    The bubble finally burst and I noticed because I felt a burning on my wrist.  Does anyone have any suggestions on how toxic the liquid is?  Or suggestions on other brands?  I like the small design of this but If anyone has experience with fitbit let me know.  This whole experience has been frustrating.