Originally Posted by pete.i
There is no way to check it other than what you are doing. There are lots of fake ones on Ebay as well that either do not have the capacity they advertise or just do not work. Either way it's obviously toast just return it. Of course if you bought it from a shark on Ebay then you may not be able to return it.
Thanks for the replies chaps. I don't know if it is worth returning the stick as they weren't very expensive. I purchased them from Amazon, they came as a set of three, two were OK but the third couldn't be formatted.
Thanks for your input though. Always much appreciated.