Chosen Solution
I have installed the memory and ssd upgrade successfully but when I boot it up to check, I am getting blank screen. The display and the power cable have been connected to the logic board but the screen is like it is dead. What would be the cause of that? I have since then replaced the original memory and the HDD and I know the system is booting up but I still don’t get anything on the display. Please assist!!
Did you follow the iFixit guide: iMac Intel 21.5" Retina 4K Display (2017) Display Replacement using the iMac Opening Wheel and Plastic Cards as explained in the guide? Using the wrong tools or using the incorrect techniques is often the cause. It’s very easy to damage the display trying to take it off. You also need to be careful with the still attached cables as you can damage things pulling too hard, then the reverse, plugging in the cables correctly. Do you have an external monitor which you can plug in to help isolate things out? I would start there.
