Mmi not working

[gibbo6901]

Hi was hoping someone could point me in right direction. My audi a6 2009 estate developed the mmi issue where screen isn't turning on and no buttons are lighting up, I've done vcds scan on the optics and all come back ok. I've looped the optic cable from amplifier to see if that's the issue but still nothing, I took the fibre cable from back of main unit in glove box and cd charger and there's red light coming from the cables there aswell both units work if I press eject on the cd changer and dvd. Could this be the mmi controller the buttons by the gear stick as that's all I can think it could be as It was working 1 night then next morning it stopped but I had cleaned the buttons with a spray but was a liquid so maybe liquid has got into the board and blown it. Any help would be helpful thanks. 

[Steve Q]

Is it worth sourcing a second hand unit?