2004 A8L - MMI interface issue
 

I have problem with MMI interface in the Audi A8L (year 2004).
My dealer told me that MMI control, monitor, CD changer and DVD/Navi unit
are working OK. However, there is no power or no lights on the control panel.
So, it looks like the MMI interface itself has problem or is defective.
If you know or had this kind of problem, please help me on this matter.
Thank you!