Sorry OP if the battery is fake, I got burned a few years back with a very convincing CF card.
A word of advice to everyone: Don't use Amazon or Ebay to buy any type of memory card/battery/filter.
Just assume that anything from a third party seller is fake. Assume anything from Hong Kong is fake. Even when your order is directly from Amazon, their system will sometimes use may different warehouses and distribution centers. These locations aren't guaranteed to have legit stock.
Ebay is just asking for counterfeit stock, don't even try.
Pretty much the only option for these type of items is either Adorama or BH.
AFAIK, some Canon authorized dealers are selling on the Ebay sometimes. So, ebay is not all the times EvilBay.
And I cannot agree with your assumption that "anything from Hong Kong is fake". Yes, I made my purchases at the Hong Kong Canon dealer. They are selling 100% genuine products and I am happy with them.
There are always risks purchasing on line. Quite a number of North American dishonest on-line stores sell counterfeited merchandises and grey market items without proper disclosure. Their operators and suppliers are from all over the world.
So, my suggestion is to buy from the authorized dealers direct and you don't have to waste your time and energy finding ways to recover your loss subsequently.