Ok you say the lights were getting dimmer and dimmer. There is a way a bad battery can cause that. To test disconnect the battery negative lead. if the lights brighten. Replace battery.
IF not re-conenct it also connect an "external" charger.... The one I have is a rather large Deltran Battery Tender model (There are many like it ) this unit has a very low current (like 2 amp max) Tender mode, a 20 amp "Bulk" mode and a 70 amp jump start mode (forget that one) took it 24 hours to re-charge my battery bank when the converter crapped out... I got a new, factory refurb, converter the next day..... FROM THE FACTORY (Ok I know here the factory is)
What model converter do you have.. if you have a hard time finding it and if both the 120 volt breakers and 12 volt fuses are behind the same door... What's the model of said door?
How hard is it to replace a converter?
Converters come in two types. "Intergerated" (See "Behind same door") these are part of the power panel and how hard they are to replace depends on if you can access the electronics without completely unwiring the panel.. Some you can. others not so easy.
The next type is a a/b "Stand alone" The A/B part is "Plug in or hard wired"
Mine was a plug in
Pull plug. Remove 4 screws, Turn unit so I could get to the 12 volt connections.. Loosen, remove wire and cap temporary.. Also a ground lead.. "Toss" in car. Drive to Factory (NOTE this is the area I grew up in so the way is well known) Walk in, get ask "how can I help you" Point to box and say "Dead" Told to go through door.. repeat of question. and answer. Put on desk.. Then came the hard part (paying for it) Back to RV. hook up 12 volt wires and ground lead. plug back in.
The hard wired you have to disconnect the 120 volt lead and protect it as well.
NOTE if yours is intergrated and a devil to access. .You can add a 2nd converter. (Stand alone)
That factory.. Progressive Dynamics.. if intergrated 4600 series.. if stand alone 9200 series (Unless you are replacing a 9100 with charge wizard.. then you re-use the wizard.. Bit cheaper)
Try to match the last two digits of the model as close as you can the original.