Right, it’s a separate (3 PCB system) for non-impact (Teal) Indigo2 PSUs (I forgot you were dealing with Impact due to you terminating your graphics power rail throughout this post), doesn’t really matter. You don’t need to separate boards (as long as you start your measurements from same state on both examples. You understood my point.
I doubt you’ve done what you claimed. You must have an impedance difference to have a circuit difference (or a shorted component, that also must have a difference in circuit impedance) between two circuits. If you’ve done a measurement at every junction (pad) and both samples were the same/similar, then both would operate the same.
No, you did a few measurements and called it quits. I’m talking about starting at resistors first. But ultimately performing a measurement at every pad, every component, until you find that comparative difference.
You don’t start randomly, you know you have a resistance issue, so you start there. If you don’t find any difference to ALL resistors between both boards, you move on to another component class (diodes, coils, etc) until you find it. After that you could move onto a different multimeter test at the previously test locations.
you’ve only taken a few large measurements (that you’ve indicated). Start at a single component type and go further.
You asked for advice on how to proceed but you won’t do the basic component checks and you’re trying to systematically troubleshoot. That would be great if you had a systematic understanding of the entire circuit, you don’t. No one has come forward to claim they do.
So you’ve spent countless hours on this and posting to the board after many days asking for a systematic answer.
We cannot give you one at this time. Since you seem stuck the advice is to change your approach from systematic to component-level (in-place). At this level it doesn’t matter, yet, if you measure 7 components in circuit because they are in parallel or whatever. Even the sum of an area can be compared to the same area on another PCB of the same circuit revision.
Once you find a region that differs you then would need to start removing nearby components to test each and follow traces.
Your free to continue whatever technique you wish, but then posting the same question and same roadblock to this post will likely result in a dead end without a change in approach.