Black screen following HDD replacement

I had a failed HDD which I replaced with a new SSD.

i was very careful opening it up, used the ifixit tool and was careful not to stress the screen when removing. Put everything back together but when I powered it up to test is the screen stayed black, the fan went crazy and the 4th diagnostic light didn’t turn on.

i removed the screen and noticed one of the pins on the v sync cable was bent so I ordered a replacement and swapped it out. Unfortunately still a black screen and only 3 leds.

Any ideas.

Ive tried resetting the pram and have tried reseating cables.