Just finished installing a new seawater pump.

Now have zero electrics at the helm. Looked for obvious disconnected connectors etc., since I was working in the engine bay.

Outdrive trim works, but it has it's power wired live to the starter solenoid.

Curious how power is routed to the helm. All I see at my battery selector switch is the large gauge battery wires, and 3 small wires hard wired to the live side (bilge pumps, etc.).

Didnt pull your lanyard / teather by any chance did you?

The indications would point me to a loose, or shorted starter fusible link. You should have 12V power making its way to the starter (main 12V wire) this wire is connected to a white (or off white) cube with a tab on it that connects to the starter. My bet is that your fusible link may not have a great connection, or it is blown. Its an easy fix, and easy to diagnose... Use a meter to check for 12V power at the end of the battery terminal that connects to it (it should have power since that comes right from your battery switch) - Then check for 12V power on the stud that the fusible link is mounted to... If you have no power on the stud, then you either have a lose connection or the fusible link needs to be replaced.

The more rare issue could be your battery switch has become faulty... If that is the case, you will have no power at the 12V main lead on the starter (assuming your batteries are connected through the switch correctly)

Either way, the test is simple... Just check the main lead for 12V at the fusible link, then at the stud the link is mounted to... Both should have 12V if the link is good. Only the lead and not the stud will have 12V if the link is bad... And neither will have 12V if you are not getting power to the starter through that lead at all (which would point to the switch, or battery connections)

Hope that helps.

The helm gets power thru the engine harness. There's a few resetable breakers that could be tripped.

And the engine harness gets power through the starter... The OP stated he just changed the seawater pump, so I'm guessing the issue is at the starter fusible link, since it is in the vicinity. The stud that the fusible link is mounted to is definitely where I would look for voltage first... If there is no voltage there, the fusible link is the culprit. Start where the system gets power first (starter/fusible link) and work forward from there.

Was the 90a fuse mounted on the starter. Was not the easiest thing to change....

That's what I suspected... (hope I helped)

enjoy!