Bought this on Ebay for $20 as it was not functioning.
So I took it completely apart and couldn’t find anything wrong. Then I decided to be smart and googled it…turns out in some modes it gets stuck and needs a factory reset (-1 and +1 keys held down when powering up).
It sprang to life but did display a low battery message…
So I did the same thing as on the Korg DS8, soldered in a PC battery holder.