Yamaha P70 - tech/troubleshooting help

[indyfan]

hi folks,

I have a Yamaha P70 that has hardly ever been used, but I believe has been plugged in for too long, and now the piano won't turn on when I press the power button.

I have removed the back, and I believe there is power from the power cord.  My multimeter has confirmed 12V.  I have also confirmed 12V at the socket on the circuit board, where the power cord plugs in.

I have followed the ribbon cable that connects to the other circuit board that contains the power switch, and assume that the red wire would be the power wire/pin.  With that assumption, I could not find 12V at the pin on the main board.  So my assumption is that something on the main 'power' circuit board is fried. 

Since all the online manual sites seemed to have sketchy reviews, I don't have a service manual to refer to.

So my question to you is what should I do next?