04a8newbie

i recently bought an 04 A8 fully loaded with every option imaginable. I got what I think is a killer deal on the car ($2000) and everything seemed to be working great, then two weeks after I bought it, the MMI screen went black and now will not turn on or close... as if it has lost power supply... when I consult the original Audi owners manual reference to the fuse panels, I find no reference to any circuit that identifies the MMI screen and when I go thru each of the 4 fuse panels, I cannot find not one fuse that is blown.. 100% good on every fuse..... where do I turn to next????? Please help!!!!! As you know there is many things mechanical that are not accessible without this system being operational... and also no bose premium sound system 🙁🙁 PLEASE HELP audi ownership is new to me and these electronics seem out of my league!!!!