I agree with everything said here.
In general (for the OP and anyone else who experiences electrical gremlins, too), you need to follow a plan in diagnosing that will eliminate, one by one, the most likely causes first.
- Battery - buy a multimeter and check it out or do as Dan suggested and get it checked out for you. A hydrometer can also easily be used to check each cell.
- Connections - are they all secure and clean? Especially the ground to the frame?
- Search for a resettable breaker and or an inline fuse as Dave mentioned above. Generally on the Roo, this will be on the positive wire a few feet forwards the converter.
Here are two more pictures. The first pic is the resettable breaker. The second is a pic of a 30amp fuse...
- Cables? This is less likely with a new camper, but is there a short anywhere? Cables can rub against the frame. Are they intact running all the way from the battery to the frame (negative for the ground) and battery to the converter (positive). A multimeter helps here, too.
Page 7 speaks to troubleshooting. If there is no DC output, check the reverse polarity fuses on the front panel of the WF-8900 Series power center (See diagram below).
First, visually inspect the fuses for any breaks; if none are found, use a continuity tester to check for continuity. If the reverse polarity fuses are blown, it means the RV battery was accidentally connected in reverse, either at the battery or at the converter. Reconnect properly, then replace the fuse with the same type and amp rating as the original “Littelfuse ” Type 257 automotive-style fuse
Consider buying this book, that does a phenomenal job helping to diagnose issues that will crop up in your ownership of your trailer:
Managing 12 Volts: How to Upgrade, Operate, and Troubleshoot 12 Volt Electrical Systems by Harold Barre
I hope that this helps.