Xbox One turns off by itself

[Zap!]

Ok, so here's what's happening. I just got three broken Xbox One's. Two of them power off immediately after powering on. The third one (let's all it Xbox number 3) usually powers off after roughly 3-6 minutes. After it powers off, if I try to turn it on again it will immediately power off. It won't go "back to normal until" until at least an hour. I'll mostly focus on that one, since I'm guessing it'll potentially be the easiest to fix. The fan spins on number 3, but doesn't get the chance to do so on the other two

 

Here's what we can rule out: the power brick. I have a working Xbox One and extra power bricks, and tried those on all three. Didn't make any difference. I can't reset (hold down the power button for 10 seconds) two of them, since they power off after a second. I did do it on the third one, and it still shuts off after a few minutes. I also tried YouTube and the 'net, and didn't see much.

 

So I took them all apart, cleaned them, and checked by magnifier for any broken or burnt capacitors, and none had any. So I then took off and cleaned each heat sink, and re-applied new thermal paste. Put them all back and same problems. After that I switched out the old heat sink on the one that shuts off after a few minutes. Didn't do anything at all.

 

On Xbox number 3, I did an update, thinking it might fix the problem. I crossed my fingers when I got to the home screen, but it soon shut down again. So next time I tried a full system reset to factory standards. After I got to the part where I put in my MS account, it reset again. I am now out of ideas. I need your help.

 

Xbox number three seems like an overheat problem, yet changing the heat sink and cleaning and adding fresh thermal paste did nothing. The fan is spinning and very clean with no dust, so how could it be overheating? Any ideas?

Edited April 27, 2019 by Zap!