Ok, let's see if I can help. If you read your own pictures you'll see that it says converter right on the unit. A converter converts 120v AC into 12v DC power.
An Inverter does just the opposite. 12v DC into 120V AC. Just google inverter generator for an explanation of why it is an inverter generator instead of a regular generator.
Check for blown reverse polarity fuses, the 40w orange ones you see in the fuse panel. Did you accidently hook up or even touch the cables to the wrong terminals on the battery when you changed it? One second of reverse polarity will blow those fuses. Then the converter won't work.
To locate the Converter in your RV just take that whole front panel off the unit
and you will see the "converter" underneath the distribution panel portion of the power unit. There's usually a tin panel in front of it to protect it. Open the flip down door and there's 2 screws near the top (I can see 2 chrome screw heads in your picture)and tip the top front down to remove the panel. Voila' there's the converter supplying 12v power to the distribution panel and hopefully sending a charge to the battery. Be careful when doing this as you are exposing 120v breakers and wiring that's dangerous. Don't touch anything in there if you don't know what you're doing.
WFCO converters a not a high quality unit and it's possible the converter/charger section has gone bad. If so they can be easily replaced with better quality converter/charger units. Go to BestConverter - Converters, Inverters, Electrical Supplies, Electronics
to find replacements.
you can check out this webpage to see what I'm talking about. It shows you how to trouble shoot the converter. Specifically page 7 of the manual. https://www.rexandsonsrvs.com/manual...ter_Manual.pdf