Dead House battery cause limp mode / no start or could there be other issues?

[FSH 210 Sport]

FSH 210 Sport, yes, I did try using the EPS switch several times and cycled both switches multiple times. I think in my case having two start batteries aggravated the situation. You are correct - putting them together should equalize the volts across them.

I left the connext screen on as we were listening to music when this happened. What was so strange (to me at the time) was the fact that the starboard engine cranked strongly but refused to even fire once until I put the batteries on charge at the dock.

I just went down to the boat to verify while I'm in the middle of writing this:

House On/Start Off: SIMRAD works but not Connext
House Off/Start On: Turning ignition key you can hear fuel pump priming, but neither SIMRAD or Connext work. Pushing start button it did fire up.
House On/Start On: Of course, everything works.

Interesting. I've never tried to run it without Connext on. Not sure what would happen in terms of the ECM and basic functions.

And turning on the EPS should not work to fulfill either needs as that is on the source side, you’d still need to have the switches on…

Thanks for running that test for us! Very informative.