New battery not charging, percentage counting down?

Good Day All,

I got a new battery off eBay, one of those high capacity ones, and had issues turning my phone on when I first put it in. I turned my phone on and got the Apple logo for a few seconds and it would disappear and do the same thing over and over and over again.

I hooked up my charge cable and got my phone in DFU mode, but couldn't restore with iTunes, I got error 2001, I believe it was. I then got my phone to the screen where it has the iTunes icon and sync cable, and was finally able to restore my phone and get it working again.

The phone shows charging, but I noticed the percentage start off around 30%, and slowly count down, instead of up. I left it on charge for a couple hours and unplugged my sync cable, and my phone shut off immediately.

What did I do wrong? Did I get a bad battery?