So I emailed the local company for these PSUs. Keep in mind I didnt buy the units from them so I was not sure if Id even get a response.

Received this:-

The solder tip of your iron will be earthed and this is a different potential to the Ov rail which is not really “0v” but simply a DC return for the +DC rail and is therefore floating with respect to Earth. I am not sure of the effect on the PSU by doing what you have done – usually a thermal trip / breaker will have activated but if it isn’t anything obvious then all you can do is speak to the manufacturer which is not us, we simply distribute. The manufacturer is a company called EPLAX in Germany and you need to call them

So I have a few options. Let's assume they are faulty. I need roughly 10A if I do a like for like replacement although I am sure that the smaller driver and board take less than 2A. I could also increase the Voltage on the two main axis steppers. Would higher voltage be better or just remain with 24V all round?

Thanks