There is, but it’s flexible depending on the purchase. I’ve successfully done one nearly a year later when I bought a used phone off eBay, shipped it back under warranty, and once the seller had it they stopped responding. Both eBay and my bank advised me to do a chargeback. I did, and got my money back.

Why not “how the crisis could be resolved peacefully”?

drop back and punt with my old i5-4590 tower

This one. It’s old, but with RAM and a GPU you’ll be able to handle streaming/transcoding.

The problem with Dell/HP/Lenovo etc. PCs, especially smaller form factors, is that they’re non-standard, as you found. And not just the motherboard mounts, but also the power supply connectors, and often other stuff too. And any feature found on a typical board, but not used in that particular model, will be missing, like multiple SATA ports, again as you found.

You could probably get a newer desktop for not much money, too.

Nazis