To reassemble, make sure you slide the little counterparts on the top of the display under the phone’s frame first. See this answer: Screen won't close tight after reassembly. To close the display after that, I simply turned the device around (on a cloth) and pushed down on the frame with a lot of pressure. Much better than trying to close each edge individually by hand.

I also discovered I have the "fusion drive" version with the hd in the lower slot. Mac mini Late 2012 Power Supply Replacement helped me enormously.

No need for logic board removal tool, just move it outward.

What I didn't find out is if you could just pop in a second drive on top and leave the old one in there; is there another caddy required?