I opened the tender. Surprise! There is the battery. GRJ's picture from the online manual and my paper manual are the same: incorrectly showing the battery in the boiler. Well, I can put off opening the boiler.
George, I double-checked the screws and I have the right ones according to the [faulty] manual. But since it's not moving at all, I think you are right, there must be additional screws.
Bob