how does the battery door come off?
On the top of the door theirs a slot that you need to pry off. Its a pain in the ass and if you don't have nails you'll need a small screwdriver or butter knife. That's what I use cuz I have no nails. You'll feel like your about to break it but you wont its pretty durable.
I like that its kinda tough... rather than having a door that will fall off after it wears a little bit... i've gotten used to it and its not so bad if you got the technique