Repairing MT-100...?

[drissa]

Just received a Casio MT-100. Inside, it looks like a bit of a treasure trove... but doesn't power on with batteries or power supply.

I've opened an Ebay dispute but in the meantime, does anyone have advice re. possible repair? The keyboard is in very good physical condition with no obvious damage inside or out. A fried chip, never to be repaired, perhaps...?