I know this may sound a little weird, but you could wrap a piece of electrical tape around the the battery and see if that helps keep the battery in position. You could also, remove the atomizer...then with the battery in place, mash the button down just once, hard.
The last resort I would suggest is removing the atty, battery and juice bottle, flush your mod with really hot water, blow dry...or let dry. Reapply a small dab of Noalox (you should have received a small smear of it in a little baggy) on the tip of the positive battery contact. I don't think this would be necessary, but if it helps...that's all that matters.
I still think, given the circumstances that you will need to talk to Rob, and possibly send it back to him for repair.