Perhaps someone more knowledgeable then myself can help on this, but I wonder if the battery pin was actually spun around? Don't knock all internet vendors just yet. There are definitely some better deals to be found online, and when paired with online reviews of vendors, it's easy to select the more trustworthy ones. The thing with ego batteries is that you can't take them apart for repair most of the time. They are meant to be disposable devices. When the battery dies, they're tossed or recycled. The lifespan on them is meant to be quite short. At most, for 300 charge cycles generally. For something that'll last longer, with more repairability, you'll want something with removable batteries. Many even have adjustable connections for those toppers that are on the longer side or shorter side then average, so you won't have to worry about the battery pins being thrown off by overtightening.