Have you called Chalet with your VIN? While black is often ground there is no real RV color standard. Continutiy may help but there may be loads on the positive wires that can't be turned off. Try the above test with the converter on then the best bet is to bite the bullet and trace the wires physically or with a wire tracer. Or with the wires connected and a voltmeter start tracing the voltage using frame ground. Maybe some one can help.
Per above you may have blown fuses with your reversed wiring, etc.
Always good idea to take pics and save them. Any non black non negative wires should be marked with black tape and non red positive wires marked with red tape. Also note how many wires on each terminals in case one develops legs and is hidden. Then take new pics.
If all else fails hold up your credit card. :B
2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland
Bob