Sorry 'bout this all, Bob
, I just need to get this out of my system...
And that system has navigation elements in it. It is relevant since we'd expect to see navigation elements on that display.
Why would we expect such a thing? Our heroes aren't interested
in navigation in the slightest. They are wrestling helm control back from M-5. If this requires opening a box labeled "Helm plus stuff", and the stuff happens to include navigation, so be it. But what we really expect
to see here is systems allowing our heroes to point the ship's bow in the desired direction. Be they manual or automatic (and preferably, of course, both), they have every right to feature all the elements of steering, including the machinery responsible for the act itself.
There are no examples of steering the ship with adjusting the power of one warp engine to cause a turn, as you allude to.
There's a pretty clear reason why I so allude. It's a way in which ships are steered in real life. We have no data on how ships are steered in Star Trek. Here, pieces fall effortlessly in place if we assume ships in Star Trek are steered the same way ships in real life are. I cannot fathom why you would so desperately resist
the pieces falling in place...
It's not as if
a) you would have a competing model you could point at as being evident on screen and therefore invalidating this model, or
b) canon aside, there would be something wrong with this model per se, or another fictional model would be superior per se, or
c) something would be gained by arguing that Chekov cannot be looking at a diagram featuring the warp propulsion system when looking for ways to influence where the ship warps.
warp "steering" appears to have nothing to do with the warp engines
Based on what? None of the dialogue bits you quoted suggest anything one way or another. If the ship moves at warp, it is being steered by warp steering (except perhaps when superentities make her fly in circles); if it does not, it is not being steered by warp steering. Dialogue never dwells on either situation, and juxtaposing one situation's helm dialogue with another's warping dialogue won't help.
Since they re-use that display it is unlikely to have any "helm and navigational control circuit" status since it would show the dead state.
Naah. It would show the system
, with "dead" and "live" differentiated by minor things we can ignore, just like we ignore most of the (lack of) graphical detail in Star Trek. Having this diagram visible 24/7 poses no problem whatsoever, regardless of what it is supposed to describe, as long as it describes part of the hero starship (rather than something they only visit that one week).
It is rather fortunate that Chekov looked down at the buttons and never looked back at that display before confirming with Spock which removes the diagram from play as containing control circuit information.
Makes no sense. You would now need to prove that
a) part of what Chekov works on is irrelevant to what he is doing, and
b) there is something to be gained from the diagram not being relevant to Chekov's task.
The first claim is absurd, while the second calls for some pretty hefty explaining. Why do you so desperately wish for Star Trek to not make sense?
In this case, it require more inventing for us to put control circuits into that diagram and then more inventing to why Chekov doesn't look back up at it again after checking some buttons to confirm that the circuits are dead.
Much more easily done than trying to explain why Chekov would be watching hard(ware) porn during working hours.
Oh, well. Display shows Chekov that items A, F and J need to be checked. Chekov checks those specific items, namely their associated switches, and observes their status, then reports this to Spock. No need for him to look back at the display. There. Feel any better?