Can't replace video data cable in iMac 2428

I used the iFixit instructions and the OWC video to try to retrieve a foreign object from the DVD drive. I got the data cable off the socket very easily, but after I did the job, I could not get the cable to seat properly in socket again.

I bought a new cable but ran into the same problem with the replacement. The screen won't work when I reassemble the computer. No apparent damage under the magnifying glass.

Has anyone else had this happen? If so, how did you fix it?