I gotta ask even though it's so basic - i assume you have all removed the radio face (2 screws in bottom corners) and checked carefully that the ribbon cable connecting the face-panel to the main radio body is definately firmly connected ?
Failing that, there is a sticky, or note, on here somewhere about a company who will repair the main radio for you. They're the same company used by Seat but it's quicker and far cheaper to approach them direct.