Not a lot has changed in 20 years, besides the no hard drives, you just slot the nvme in to the slot, just assemble everything outside the case, CPU on to motherboard, cooler on, ram in, nvme in. Make sure the standoffs are in the correct place and get screwing

.
Unless it's a cooler as big as the A620 and Peerless Assassins ;-) cause you'd struggled to get to the CPU power and the screw on the top left. Though for the CPU cable and motherboard getting extensions can make it easier apparently, as you plug in the extensions before you mount, feed them through the holes and secure behind to the actual power supply.
Also helps with modular power supplies.