New house battery, now steps & inverter not working.....

If you were connecting the batteries and had the unit plugged into shore power, you might have easily zapped the fuse in the converter circuit. Did you have it plugged into shore power while changing the batteries?

I made the fatal mistake of hooking my new batts up reversed.
Cost me a converter also.
Best part I even took pic's on old hook up so not to make a dumb mistake.

So double check the batt conn. Than your Converter/charger.

99.99% of these problems are preventable. I should know - the school of hard knocks kicked my butt when I first started wrenching as a teenager. I guess there should be a sticky about this

BEFORE YOU TOUCH ONE WIRE ON THAT BATTERY!

LABEL IT.

I got so lazy, when I went (yawn) to work on the electricals, I (yawn) went to the disconnect switch (yawn) and turned it off, before I disconnected the SINGLE RED positive cable and SINGLE BLACK negative cable. People will spend a fortune for unneeded gizmos then practically end up in the cardiac ward because they didn't bother to find out how to make battery management simple enough to meet the needs of the laziest of engineers. Trust me, electrical engineers, good ones, have Simple to understand battery management systems. I assemble clean stuff, paint the POSITIVE with RED spray paint. I mean GO FOR IT! Lugs, terminals, a a nice splotch around the post. Good enough to ID at twenty feet. The SERIES connections, the NO-TOUCHEES, linking batteries for series I paint with GREEN enamel. I'm going to have to remember to get a can of YELLOW enamel and do the negatives as I really like the idea of doing low voltage negatives in YELLOW, including wire insulation color. The feeder and circuit negatives.

Cycle your battery disconnect to OFF, then back to ON.
Check to see if any 12 volt items work with shore powerdisconnected, then try with shore power connected.

1. Did you clearly label all the wires at the battery before you disconnect them? Note HOW MANY WIRES were connected to the positive terminal and how many wires were connected to the negative terminal and then do "A Sponge count" after the operation was over?

#2
Go back and re-read # 1

Did you get the polarity correct? All wires reconnected in the right places? Did you replace a 12v battery with a 6v? Do you mean converter instead of inverter? Take a picture before disonnecting?