Xbox Series X not booting

The console is not used that much, on average 30mins a day the last 3 months and the time before that its been unplugged.

One day it did not power on, not via controller or the button on the Xbox.

I suspected the PSU but that gives a steady 12v out on all pins. Both bords also have 12v on them when I meassure.

The USB ports gives power if the console has power.

Nothing happens when I press the start button or try to start it with a controller.
(The fan does not spin, no LED lights up no nothing)

I've also tried starting it with a controller pluggen in via USB.

Any idea of what could be broken?