Hi sixwheeled,
Thanks for the reply and the link.
So it is possible that the ribbon is broken even if it looks ok. I already checked it but didn't see any damage so I thought it's a screen problem.
As I said in my reply above, phone's ok with tv out. So it really is most likely a hardware fault... I was hoping otherwise. Thanks again.

Edit: after reading about your experience with the ribbon"screw" I decided it will have to go to Nokia Care. Yours is not the first account on that screw, I wouldn't want to go through that experience.