My copper washed Zincs:
Cause: Your converter is not charging your battery
Why it worked on delivery: The delivery truck's alternator kept your battery charged while it was delivered.
Why it died: You used it till it was dead before figuring out why it was dying.
Why the converter won't work now.
A converter will not charge a completely dead battery. Remove the negative battery cable from the battery (ONLY). THEN:
1) Switch the 120 volt breaker marked Converter to OFF; then back on - check to see if that fixes it and you get your 12 volt system back. If so remove the battery (noting which one is pos and neg (MARKING THEM so you don't hook them up wrong!) Then get the battery tested and recharged with a good battery reconditioning charger like: Battery MINDer | 12 volt 2/4/8 Amp Battery Charger, Maintainer, & Desulphator
2) If that fails to restore 12 volt DC power, then the problem is the converter itself is not working (it does happen). (attached troubleshooting guide is for the WFCO 8900 30 amp converter but the idea is the same).
1) UNPLUG THE CAMPER and since you already reset the black 120 volt breaker marked converter above, remove the cover panel (if you are comfortable doing so). Examine the two 40 amp reverse current protection fuses (they are orange if you have 40 amp fuses) and replace if damaged. If one or both are blown CONFIRM that the battery was installed properly.
Retest without the battery and if you get 13 volts or better, retest again once the charged battery is reinstalled.
2) Examine the wire coming from that first breaker on the right (the one marked Converter) and make sure the wire is attached. It is possible the wire was installed loosely and has come apart, broken off due to a nick in the copper when the insulation was stripped, or burned up due to a high resistance connection at the breaker. Repair connection and retest if so.
3) If connection is solid at the breaker, remove the entire unit from the wall and examine the converter itself. Make sure none of the above happened at the converter connection. Repair connection and retest if so.
Examine the wire from the DC side of the converter to the fuse board for open connections. Repair connection and retest if so.
4) Examine the converter for burned components and have them replace it under warranty or just call and tell them to send you a new converter. You may need to walk them through all the troubleshooting you just did.
If you got this far, replacing the converter itself is a snap. If not, you should call for a technician to come out and fix your camper under warranty.