Juno 106. No sound and unresponsive.

[ginseng]

Hi, hopefully someone can give me a few pointers.
I've picked up a 106, seen plenty of use. It has no sound. I can't access test mode. Unit basically powers on and all the LED'S light up, and you can't turn them off.

Internally, I can't see any evidence of blown electronics (I'm no tech), checked all the internal fuses I can see and they all look fine.

Any idea's where to start looking? I've downloaded the service PDF and I've got a cheap multimeter.

Any help appreciated.