Fixed it.

Problem 1: The ram wasn’t seated properly. It clicks into place a few millimeters before it’s pushed down far enough. Push until the gold connectors are no longer visible at all. Mine seemed like it would break, but it didn’t.

Problem 2: This one was minor, but I had to hold the power button down for 5 or 10 seconds before it turned on. This isn’t usually the case, it’s only after replacing the ram.

Same-ish here. I swapped out the original ram for 32GB (2x16) from Crucial. Then the Mac mini won’t turn on again. I put the old ram back in and it turns on, but only recognizes one slot.