I can't remember, but I think there were only 28 presets, and the rest were writable. The first 28 were fixed - try to edit them and see if you can write to a location in the first few number banks. Sounds like the internal battery is gone if there are no presets written.
Everyone, and everything I listen to is my teacher. Every instrument, every voice, every sound in nature ... they are all my private tutor ... 24/7 for free.