Display Data cable or connector or LCD problem?

My MBP boots fine and external display (DVI) works fine all the time, if the DIsplay Data Cable is disconnected from the logic board.

My MBP boots fine only some times (~20% of the times), if the Display Data cable stays connected, but the LCD screen display stays really really dim (almost blank).

Could it be the Display Data cable or connector on logic board or on LCD screen or the screen itself? Should I open the LCD screen to check the connection? How do I check LVDS (video) cable connection (assuming it is different from the Display Data cable)?