Thick black stripe on iMac screen after attempting HDD to SSD swap

Take a look at this question I suspect you have the same issue: I've got vertical lines on my iMac 27" screen.

"Exactly the same problem with me.

No way to repair this? I´ve taken all the extra cares doing this, still encountered the same problem... :(

When plugging it back, a black bar on the right side...

Any suggestions?"

You have the same problem so just read all proposal tips abowe and I am sure you will solve this problem as those guys did. Good luck.

"I know this is a very old thread but I believe I have solved the mystery. I purchased a used 27 iMac 5k with 3 black lines on the right hoping I could fix it. I tried everything to figure out why it was bad, GPU, cables, cable connectors, etc. I've also read every question on this topic on this site. It was not until I removed the metal shield on the top rear of the LCD that I saw that it had several cable ribbons from the long PCB connected to the screen. At first I thought the leads were bad, but upon closer inspection I noticed three of the ribbon cables were cut. 3 black lines on the right. 3 ribbon cables cut on the right. It appears that when the last person tried to get into this, they may have used a sharp blade or razor to cut the adhesive. In doing so they sliced too deep and cut into the ribbons! I don't know if the ribbons can be replaced or the rear PCB. I have never seen it sold anywhere and the soldering is so fine it can't be done by hand. :(

See pics:

https://imgur.com/a/31kMq9I"

"i think I am with the same trouble after changing hdd

any tips are very welcomed"

"I opened my late 2013 27 in iMac to replace the broken hdd earlier this week and when I put things back together the screen stayed black (4th diagnostic light isn’t lit either,) one of the pins was bent on the vsync cable so I bought a replacement but still the screen is black. I was very careful with the screen, used the ifixit tool etc.

Any ideas?"