XB One failing to turn on


Yes, I have used the wonderful Google, however, nothing points me into a good valid direction.

I have an Xbone sitting here that a friend sent my way because it was acting up and they wanted it fixed if possible. It's acting as if it's the PSU, but at the same time I can't confirm that, because the owner has stated twice now that they attempted to use a known good PSU on it, with the same results.

So, here's what happens - Xbox is plugged into PSU, psu goes from Orange to White for 3 seconds then back to orange. I press the power button, and the PSU flicks to white for a second then back to orange and xbox immediately turns off before the fan can ever spin.

Now here's the fun part, if I let the PSU sit disconnected from the Xbox and plugged into the wall for ~45 minutes or so, and then plug it into the Xbox, then all is *usually* good. I can turn it on, update things, play games. But the next day I come back, and it's as dead as a door knob, gotta unplug the PSU.

So, ideas?