Very old, battery would not hold charge. Costly to fix at Apple store. I'm fairly handy with this kind of stuff. I could tell you stories.
The instructions were excellent. I followed them to a T, though removing the two plates was better done with a small pocket knife blade.
DIY when you can, but check the net and practice alot. All the time, in fact. I repaired a wall clock that was in my family home in 1953; and an old lighted globe, two in fact, that are from the 50's.