I've acquired two (2) new TB50's and they are totally dead. Placing them on charger they are not taking a charge either(charger just blinks) . Of course they are under warranty, but wonder if there's something that I can neither find on research nor any posts/threads. I have multiple chargers so that's not an issue, as my other TB50's charge fine. I just find it very odd that two new batteries are dead and cannot take a charge? Any secret tips?