Hello from Australia

[Brad93]

It sounds like you really know what you are doing.
Is there a forum thread/s that you can point me to that educates on this topic? I have a feeling it's knowledge that comes from trade experience though.

Like a lot of things you can only really learn by doing.

Youtube is a good place to learn how to test individual components.

I'd start at the point where the power comes into the PCB and trace along its path.