Console starts but turns of after a few seconds

Hi,

After changing Themal paste (to arctic mx-4) the Xbox one X starts but shuts of after a few seconds. I have reopened it 3 times and carfully connected Everything so that no cord is loose and I also took a look at the processor to see that no pin there was hurt (and changed the thermal paste again.

When I push start I hear the start “pling” and that the hard drive is starting but I do not hear that the fan is starting. I am now thinking that the fan might be broken. Could a broken fan give the result that the box shuts down after just a few seconds? Or could it be that the HD is broken and when it fails to read it the box shuts down?

Any other idéas what could be wrong?