Nothing works

[CEustice]

The house batteries on my 2018 Thor Chateau 31W died after their first winter-over, so I thought I'd just put in some good quality new lead acid. first thing I noticed upon disconnecting the old batteries was that there was no battery-to chassis negative wire. is this normal? Or have I been driving around with no house batteries, so to speak. we never dry camp, just go from campground to campground, so I'm wondering. the ONLY negative wire goes direct to the inverter.
Upon installing new batteries, wire for wire, nothing works. Nothing. Pushing the master switch button produces total silence. I've checked 12V to the inverter, good. Ive checked what fuses I can find, all good. I've checked the relay I found located forward of the battery box underneath, it appears to be set, but its actually not possible to reach, so?

I know that the master switch button closes a relay somewhere, but I don't where, possibly underneath the refrigerator where the inverter is, but that is such a rats nest of wiring I'm totally lost
What did I do to get myself into this predicament? it started out so simple. Help!

[Beau388]

Batteries won't work without a good chassis ground. All the circuit breakers, high amperage circuit breakers and relays work on the positive side of the battery. I suggest you dropped the ground cable when removing the batteries. Look in the back of the battery compartment or under the coach for the HD chassis ground cable. Since you have an inverter, the ground is probably a 0/0 cable or possibly a 0/2 depending on the length of the run.

[SANDDOG]

Wow I I agree got to have a ground so sorry.