Disklavier

It's a wonderful Christmas Eve,

FedEx arrived with a new power supply circuit board from Yamaha. (not the 
entire black box)   I didn't have to go to the dealer to borrow parts.  It took 3 
meticulous hours to disassemble and reassemble the black box... digitally 
macro photographing same and marking cables and plugs as I went to make sure I 
had the ability to reverse the process without error.  (The power supply is 
tucked way up and in the black box and the MIDI circuit board has to be removed in 
order to even get to the power supply)

I just powered up the piano and it works!  It's playing Silent Night as I 
type.  My wife is speechless as she thought I was going to blow up the piano 
after she saw all of the wiring harnesses hanging just 45 minutes ago.

One minor problem; when I power up the piano I get the message:

Sensor
Led On Error

When I push Play, the piano plays normally and the error message goes away.  
What does this error message mean?

Thanks again to the group members who helped me through this process.  I 
appreciate all of your input.

Merry Christmas and Happy New Year

Jim