Need help fixing a FSP450 PSU

[Asterix]

Hi!

I have a PSU type: FSP450-40UGBBF.
When connected to a motherboard the fans spin slightly.
But turns off. I have measured the 5v rail.
This was missing.
I checked resistance it showed an open line on the 5V rail.
The 12v shows around 300Ohm.

After this i measured the wire wich was not broken.
I checked the resistance in the pcb wich was an open line the first time.
Now it is around 200Ohms.
I thave the exact psu once more and i compared the measurements to each other.
They Are in the same range. Nothing out of the ordinary here.

But it still wont work.
Is there someone who can tell me what i should measure?
Or maybe has the knowledge of this type? or a schematic?