I too also ordered another back cover from China, unfortunately ran into the same issues with the back snaps. I ended up using my original backcover... with this workaround:
Take a razor blade and gently peel the adhesive contacts away from the back cover. Then place 2 small strips of duct tape (stacked) underneath and glue the contacts to it. Voila! Closes the gap nicely and works like a charm! :D
I don't see this problem recurring after now that the gap has been closed!