Screen black after HDD replacement

I have a late 2009 iMac 27" and the harddrive died recently, so I took it upon myself to replace it. I followed the iFixit guide and everything went well! Managed to find and format the drive and restore everything from my time machine backup.

After maybe an hour into the restore I noticed that one half of the back-light was faded. At this point I didn't think the issue was too big so I let the screen turn itself off during the restore and figured that I'd have a look at the issue after it was completed.

Anyway I go to work and come back and the computer is off. Apparently there had been a power outage in my neighbourhood and we were without power for an hour -- I rebooted it and it sounded normal but the screen would not turn on at all. I used my rMBP and screen shared to the imac and, yep, it was working perfectly, but the screen stayed blank.

Any ideas of what might have happened, or if there's anything I can have a look at? Perhaps a ribbon cable is loose? Open to trying anything, happy to write the thing off, I don't really use it for anything other than a screen for watching things in bed, second monitor for macbook and plex media server.