iMac display won't light after RAM replacement

I recently replaced the hard drive on my late 2013 iMac desktop with an SSD.

Later I decided to upgrade the RAM. So I followed the instructions on iFixit and reassembled and now the display won’t turn on.

The computer turns on and I can hear the chime and the fan running and if I tap keys on the keyboard it makes the bonk noise at me but there is no image on the display.

During the recent disassembly I damaged the two side wifi antennae so I simply unplugged the two temporarily from the logic board.

One of the ribbon cables seemed slightly damaged at the end so I got a new one and replaced it. Still no display.

The machine powers on and seems to be running but there seems to be no power to the actual display at all.

Please help. What in the world am I missing?

Thank you