Xbox One - Was turning on then immediately off, now no power at all

This is my original Xbox One that I’ve owned for 4-5 years, but it’s been in a cupboard for the last 2 years since I got an Xbox One X (so its history is known - no damage, no previous repair attempts). I thought it was finally time to sell it so I dug it out, but when I went to test it I found it would not boot.

At first it would power on then immediately switch itself off. The power LED would light up, then go off again, as the console made the beeping sounds for on and then off again, all within 1-2 seconds.

After trying to boot several times (including using the Sync + Eject + Power combo to get into the Xbox Startup Troubleshooter/recovery mode) it stopped beeping altogether and the only response I was getting from the console was that the power LED would light up only briefly when I touched the power button - it would barely even reach full brightness before fading off again.

After several more attempts at powering on, the console stopped responding completely. No apparent attempt to power on at all. This was the same even after unplugging the power supply, leaving it overnight and trying it again the next day.

I bought another console from eBay, with another power supply. I tested this console and it was fully working, then used it to test my original power supply and that works fine with this second console, but my original console still does not work with the second console’s working power supply. So I think that rules out power supply.

I’ve taken the console apart down to the motherboard and closely inspected it for signs of damage or burned out components - there’s nothing that I can see, only minimum dust. 5V standby voltage is present but I noticed that when I try to power it on there is a very quiet clicking/ticking that seems to be coming from the silver 16v 470uf capacitors near the power socket. I checked them for continuity and they seem to be shorted - both legs are connected to ground. I’m pretty sure this isn’t supposed to be the case, but this is about the limit of my knowledge.

So does anyone here have any idea what the problem could be? Do these capacitors need replacing? And even if they do, are they the cause of the problem or just a symptom? What else should I be checking? I’ve got the other console to make comparisons with if necessary.

They aren’t both meant to be ground they may have worn out due to age

That’s what I figured - but after watching a couple of repair videos on YouTube and checking what they checked, I’ve discovered that one of the mosfets on the 12V power rail has gone, and on the console in the video that had caused the entire 12V rail to short to ground, so if those capacitors are on the 12V rail (which I’m pretty sure they are) then that mosfet could be the cause of everything. So I’m going to replace that first and go from there. Just waiting on the parts…