iMac 27inc 5K late 2015 don't boot anymore after screen removal

Hi all,

My wife work imac 27inch, 5K, late 2105 started being very slow and we decided to buy a ssd to replace the old 1tb hybrid drive.

I carefully removed the screen using the ifixit tool kit and did plug the new ssd drive in place of the "old" 1to drive.

But when I did take the imac to "test" if it booted sucessfully, the screen "fell" from the back of the imac, and both of the connectors of the screen (power and data?) removed themselves from their respective connectors on the main board.

I don't think the screen has any issue as it look perfectly fine. I'm unsure about the data cable though...

Issue is that, I now plug both of the connectors, press the power buton of the imac, and except for the fan I can "feel" powering up, nothing happens. No "boot" sound, no image on screen, nothing.

I will go back to her office in the afternoon and will send some pictures of the connectors and cables. I hope someone here will be able to give me some good advices to get this fixed.

Thanks in advance for your help guys !