Have you got a plastic spudger tool? If so you might be able to use it to carefully lever it out without causing any damage...
As Mal said, the mechanism for removing the battery cover must be in the unlocked position otherwise it's also holding the battery in place.
Also, that stick of RAM doesn't look like it's seated properly - you can see more of the contacts at the top end of the stick.
Yeah double check the locking mechanism for the battery bay cover.
Also the ram may look misaligned but that black strip covering the contacts might also be misaligned. i noticed that a few times on macbooks/pros upgrading memory that some of the serial number strips on the memory module area arent aligned exactly on there.