Now (still being conscious of not damaging the ribbon cable), you can start pushing the whole assembly out, power button first. I've marked the power button, so you'll know what I mean.

As you you continue pulling it all the way, toward the end, it'll get stuck, and you will need to press the underside of the white plastic a little, to get it out all the way.

If your batteries are stuck, then this is when you will be able to remove them. The space is now clear, and you can use something like a long screwdriver, to poke through the cylinder and push out your stuck batteries. (I recommend pushing them out, the same way you put them in, again to avoid damaging the ribbon cable).

There you have it. You're done.