Hence, the data cable or some other contacts along the screen are at fault. Does anyone know if there are contacts along the bottom edge, that might have been damaged and would cause these dark areas? My logic says that the info for these bands isn't getting through to the screen from the mainboard, and that the contacts related to it are damaged. It's the only place where I made contact with anything other than the edge of the screen. One quick screen question for anyone who might know iMac lcd screens - I did run the pick along the bottom of the screen to remove the adhesive there. Hopefully that's the problem and not the screen itself. I'm going to get replacement connectors and try that. It's the only step I recall having difficulty or concern with while removing the screen. They are very small, and I'm guessing fragile, and that I damaged a pin while removing or connecting. My first guess was that I damaged one of the connectors. The link you provided is one of the references I used. I'm contemplating buying the glass front and rebuilding it (cheapest first attempt) but have no idea what's involved. Any manuals or references/books on screen repair would be appreciated as well. If its the screen, would it be to the glass front panel ($50), or something else needing a new screen ($500). Would this be a bad cable, where I damaged the plugs reconnecting or would this more likely be damage to the screen itself?

I'm wondering if anyone has experience with this and would know the more likely cause. Obviously I've damaged something taking it apart or reconnecting it. After that I get the three black bands permanently blocking the screen (there is no image across them at all).

When the computer starts booting up, the screen is white and the bands are black (screen pict 2). When I plugged it in I got the 'lit up' black screen but with 3 new grey bands running top to bottom (screen pict 1). Everything seemed to be going well until I reconnected the screen. So I opened up my late 2013 iMac, removing the lcd screen, to access the inside (I followed a youtube vid and online guide).

Imac 27 late 2013 glass replacement