We have a temperature controlled testing oven at work. I set the oven for 50 degrees C, let it absorb heat for half an hour, then took it out. I had zero luck with either the plastic pry tool or the suction cup, so I carefully pried up the indicated side with the sharp pointed tip of a dental pick until I could get the plastic tool into the crack opening.

Here’s a trick you can use if your black tri-wing screws would rather than strip than come out: the reason they’re stuck is that Apple put adhesive on the threads, and if you apply heat you can defeat the adhesive. Once I stripped the first one I realized what was going on, and I put the tip of a soldering iron on the remaining screws for two minutes. Presto, they came out easily. If you strip one like I did you can either break the plastic like Al did above, or you can use a Dremel tool with a cutting disk to cut a slot in the head of the screw, converting it into a slotted screw head. You have to judge it carefully: deep enough to get a bite on it, not so deep that you destroy the integrity of the screw. Also, you have to mask off the surgery site: I put down paper everywhere except where the screw was, then covered the paper with aluminum foil. The foil protects against the sparks created by the cutting wheel, the paper insulates the circuit board against shorting by the foil. Not for faint of heart.

The question I have is this: the 2017 iMac 21.5” had a modular CPU assembly, meaning it was socketed and could be replaced or upgraded. Does the 2019 model have this feature? Or is the processor soldered directly to the board?