Xbox one overheating as soon as I turn it on

A lot of the OEM thermal pastes “expire” in 2-3 years; maybe 4 if you’re lucky. If you’ve never opened it up and it’s LONG out of warranty, what I would do is dust the fan/heatsink and put some fresh thermal paste on to rule out a common problem. It doesn’t ever seem to matter what it is - even if I pick up a used laptop the second I take that heatsink off the paste is dried up and dead.

Personally I would use Artic MX-4 instead of Artic Silver 5 like iFixit sells because I’ve found AS5 to not cure right and in “nuisance” devices, it can be annoying to fix again with a good paste. However, the Articlean they sell is worth using. I would class these as nuisance devices due to the work needed to get to the thermal paste.

The guide for the heatsink/fan can be found here and the thermal paste I recommend can be found here.

Just curious as to what you mean by “tried thermal paste”. Could you describe the steps you followed and what it looked like (was there extra paste squished out from underneath the heat sink?) Is there a heat sink on it?

When was the last time that it worked perfectly? Did it get jarred or something spilled on it, maybe a power surge?

When you look at the main board closely do you see anything that looks like it doesn’t belong? Blown capacitors, black or scorched areas, areas with dust blockages, etc.

Does it power down instantly or does it initiate a proper power-down sequence. Are there any noises right before it turns off? (bzzzz, whirrr, bonk, tink, pop) I know it seems unprofessional to describe things like that but it actually can help alot.