Operating computers in the cold

Desiccant sounds good at first, but these do "fill up" quickly. I have dozens of these bags in a 3D printer filament storage container. Even though it is completely sealed (with a gasket), all those bags are only good for about a year. Then they all must be baked at 110degC for 8-12h to rejuvenate them; moisture is insidious.

If you try this, place a quality hygrometer inside. Will likely find that the humidity stays low for only a month or so, even with a good seal.

The moisture alone probably is not causing the inability to start. The way most computers and power supplies are designed, just is not favorable to low temperatures. Very few are, because that is not a typical use case for a computer. Section 5.6 of the RaspberryPi4B says that is good down to 0degC - but then must consider whatever power supply is used for it. The characteristics of semiconducting materials changes as temperature changes, so functionality at low temps has to be something designed into it. Once had a quirky home computer that "complained" at 19degC and refused to run at 18.

If it were my machine, I'd put a heater (like a hair dryer on low setting) near the computer, along with a thermostat. Set the thermostat to say 20degC, and just let it warm up until the thermostat starts cycling. Of course need to be careful nothing can get too hot. Warming should take an hour or more - rushing it is not advised; the whole computer needs to warm up slowly. Then run the machine. That may be easier than re-engineering a quirky power supply or replacing the computer.  Unless anyone knows of an industrial-rated computer (and power supply.)  

One Solution is to get a industrial second Hand PC. I have a Beckhoff which i use with my machine for about 4-5years now and Not a Single Problem. And where i live Temperatures are as low as -10C in Winter.

Hard drives dont like cold.
And if you running them out on the floor make sure you have a backup of the HD cause one day you gonna turn it on and it’s gonna say no HD found.

I had two hard drive stop working in my un heated

Now my mill has an intel nuc with solid state HD.