Well, jailbreak applied. Can't get SSH working on it yet (because it is late and I am tired).
But it is old enough that the DRM can easily be stripped off any legitimately purchased books.
So, for the few authors who insist on *only* releasing on Kindle, I can now read on my other devices.
Not bad for a night's fiddling.
@Edent I bought one recently to use as a passive display for #HomeAssistant but I reached the same stage as you, jailbroken but nothing more.
I'll get there in the end!