White stripe of dead pixels

I used a razor blade around the edges to release the adhesives. It's the bottom strip that gave me trouble, it didn't want to release easily. I didn't think I forced it hard at all, but I guess the retina displays are super delicate.

As for the SSD, I've got it installed with the SATA cable. (There's a PCIe option??) I used the OWC thermal sensor. I tried bypassing the thermal sensor too, but still no dice. Data was duplicated to the drive using CCCloner.

@chedley - OK, I suspect you sliced the one of the display cables. A common issue when using a razor, your not the first. Get the pizza tool!

If you got a HD system you can add in a blade PCIe SSD following this guide iMac Intel 27" Retina 5K Display 2019 Blade SSD Replacement. A Fusion Drive system will have the blade SSD but it will be quite small and not very useful, but the OWC drives can offer some real performance improvement!

Cloning! Sadly, cloning is no longer the way! I haven't used it in over 15 years now! While it can be useful when duplicating a data drive it is useless on a boot drive, more so with APFS based macOS's.

So... Unless your original drive has a problem, I would just put it back in and get a 500GB/1TB blade SSD to give my system the zip it needs. If your drive is toast or you just need to get a bigger drive then put in what you need. but, this time just install a fresh OS from the Internet recovery option builtin your system and then using a SATA to Thunderbolt case to hold your old system drive restore it to your new drive using Apples Migration Assistant services.

I doubt I sliced any cables. Here's a pic of the maximum depth of my blade:

https://photos.app.goo.gl/n9f9PM3dGy8ZBS...

As you can see, the cables below are practically miles away. And upon close inspection, no visible damage.