My nails aren't long enough, and I seem to have fixed it anyway by beating the crap out of it with my fist. I contacted the seller, and apparently the battery pack had constantly remained attached since 1996 (serial number indicates a 1996 production date) or so. It attaches and detaches the way it's supposed to now. I was worried about having to send it in to you for the mods I mentioned in the email the other day with it stuck on, but it seems I won't have to worry about that now.
I did notice before I tried to remove it that there are cracks on all of the little hook things that hold it in place. The cracks do go all the way through and are visible on the other side, but they didn't get any worse from the force I had to use to get the damn thing off. In fact, aside from those cracks and a few scratches on the screen, the Nomad is basically in mint condition somehow. Its previous 2 owners took excellent care of it.