The wire harness on the bottom going through the hinge should plug in to the MBD on the bottom You might have to take the bottom cover off but make sure it's seated into the jack. Also check for a busted wire in that harness.
The fact that you have external video means that your onboard video circuits are working.The long narrow board is the inverter and it's working because you have a backlight. I doubt if the screen is bad. Do you get anything when you first turn it on?