Surprising or not, it's a fact. I have six of them, all rehabbed by myself. I'm quite sure of it.
As someone else said... trying to force the battery cover off is a good way to screw it up. Take off the bottom plate and soak the whole shebang... try a light vinegar solution first, that will usually do the trick without anything toxic. If the simple soak doesn't do it, use a sharp blade to pop off the hump that covers the battery on the inside of the cover, and try the soak again. The hump is easy to re-affix. From there, if still no luck, move on to stronger solvents. But I've never needed it, and I've worked on some that were really burned and frozen.
Ah, good, the voice of real experience and expertise, not one of mere speculation!!!