Disklavier

Okay, its embarrassing to ask such a simple question here at this high level forum but I've tried to look it up to no avail, and maybe the question will help someone else.

My Mark IV Disklavier is stuck in standby mode, I can neither turn it off, nor turn it on. The Faint green light just blinks. I have tried a very hard reset, but when the power is back on it goes back to standby mode. The PRC and the tablet appear to be working fine, though obviously  they can't communicate with the piano. 

Best regards, 

Lynda