If switched off (yes via the power reset button rather than pulling the power plug), left some time and then powered up. It plays dumb, display echos the key presses and midi functions normally but no sound out of the built in speakers unless you wake it up going into demo mode for a bit. Nothing wrong with mute/standby functions of the main amp. No flash memory card used with it but are there switch contacts in the card slot that should be open or closed and falsely registering a card is in the slot?
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on