Ok update it works now;
Bought 2 pm6-600's for cheap at a auction.
Swapping out the original with either of these seems to solve the low voltage psu problem.
System starts up, low voltage supply works, all leds are on.
But when starting jogging there came a lot of new/unexpected problems, which wasn't present in the original.
With the new module, lets call it B.
I/O configuration error driver PROFISL
A message of overcurrent on Axis 3
smoke came out of the motor(one of the connectors on it) along with a overtemperature message on Axis 4.
With other new module A there were similar problems but no smoke or overtemperature.
But very wierdly when I started moving A2, all of a sudden A4 and A5 jolted very quickly for a short moment.
I measured the wiring resistance of the phases in the motor cable(on motor side and cabinet side), theses measurements did differ for some axes. Most were 0.004Ohm and some had no continuity, one had 142Ohm.
Then I swapped out just the low voltage psu of the original with a new one. Using the original module again it started up and I could jog without errors/warnings, great !
I did the wire resistance measurements again and it was the same as the faulty modules, so I don't think it has to do with a faulty connection.