I had an Intel s2600 with dual Xeon and 120 gigs of RAM. It seems like such a good idea to run that as a home server. However, the amount of power that it used because it was older was way too much.
I ended up hunting on eBay and found an old Asus motherboard, Intel chip, ram, and a pny Nvidia card.
I bought refurb hard drives from serverpartdeals and a new case from Amazon.
I recommend starting with a chassis you want and working backwards to help narrow your scope.
I know you wanted smaller but heres what I bought. SilverStone Technology CS382... https://www.amazon.com/dp/B0CKTYSZV9?ref=ppx_pop_mob_ap_share
Also, I run truenas scale with a bunch of apps. Ssd z1 for os. Ssd z1 for transcode and caches. And then 4 drive set for main storage and another 4 drive set for backup of the first set.
I'm not qualified in any sense to speculate, and so that's exactly what I'm going to do.
My first thought is that there is a configuration happening to bring it home which we already knew, and there is a bug or test tone that was activated and since no one writing the code is there, they just didn't notice it is still running.