Reassembling the iMac is not simply following these instructions in reverse order (sorry, author).
Before embarking on the home stretch, it is very important to carefully study the guide about the Adhesive Strips Replacement (iMac Intel 21.5" Retina 4K Display (2017) Adhesive Strips Replacement - iFixit Repair Guide), as this a tedious and time consuming process. Perfect alignment of those adhesive strips takes some concentration, because you will want to have your display panel back nice and tight and fully aligned with the case. Once all strips are in place, the 2 display connectors need to be gently reattached to the motherboard, before closing up the panel. I took my sweet time for that step, and thankfully have a perfectly aligned display panel back in place looking no different from the factory fit.
While this is a good instruction guide, I recommend to also look at OWC’s instruction video about drive installation, before starting the exercise. Those install videos are very detailed and useful.
This is the least accurately described step (sorry, author). While removal is easy, inserting the new drive in its place is a bit tricky. The key here, is to insert the new drive with its rubber bumpers back in its space, so that it is fully seated down in its place *before* the connector can be re-attached. Once it is seated in place, use the flat end of the spudger to gently manoeuver the connector back into place until it is firmly connected to the drive.
This step should be done with extreme caution and care, as this step 19 is not described in great detail (sorry, author).
The first (most outward) cable will slide out by gently pulling it by its tabs. The second (inner) cable is more tricky, as the locking lever must be moved backward first, before gently pulling backward on the cable connector. The angled tweezers are useful here, to help lift that locking lever, because fingers are too big for this.
Using glass removal suction cups will avoid running this risk of damaging the camera (or any wiring).
Here’s where OWC provides glass removal suction cups, which is a better solution than plastic cards.
The suction cups help to easily lift the glass panel, without risking the damaging of any internal wiring that the plastic cards could cause.
The key thing is to never put any force on the opening tool when working through the tape. Just roll it back and forth with ease.
This part of the exercise should be done with extreme patience. I took my sweet time with the opening tool, rolling it through the entire panel and enclosure gap over and over again, until I was very sure no parts were sticking together anymore. And when I thought I was I done, I decided to do it over again.
I used this service wedge but also found it a very tight fit. The same stabilization can be achieved by using a big rolled up towel.