Machine doesn´t switch on

I am looking for a PSU.

Anyone who sells?.

That’s a custom part, isn’t it? If so, the only source might be GF and they are unlikely to sell you a power supply by itself. In that event you will be looking at a $400-1,000 repair including round trip shipping in the US or Canada. Elsewhere I think that you have to pay on the order of $1k or more just to get it shipped to GF and back. To make it worse, if they do repair it they won’t tell you what they fixed or give you any real sort of cost breakdown.