The plastic round casing for the battery is hard to open. The product does not give you much instruction on how to open that thing. It only have instruction on how to put the batteries. I emailed the company I bought it from but did not get any response. I also cannot find any information in the website on how to open it. I broke a nail while trying to open it so i tried to use a crew driver & still wont open. Perhaps it will need a whack with a hammer. I hope somebody can read this post & help he open that plastic. thanks