I purchased 5 of these for the discount and today I used one to replace the burned up circuit in one of the batteries
SKU 1306607 and it's working for now. I didn't check the other 4, but at least I can see it worked for many others so I'm not sure how unlucky you need to be to have both of them not working.
It might be too late now but maybe you can check it better if you used it properly.