No DC Power

After re-reading I definitely think it's the batteries. Despite being new batts, you said the charger was fried. So, those batteries sat with likely parasitic draws and nothing to re-charge them. If they went to a complete discharge, they are toast. I had something similar happen years ago, brand new batteries completely discharged, my charger wasn't working and they never recovered. 

does your trailer have a battery isolator switch, or a storage switch it is sometimes called.  if so make sure that is on, don't ask me how I found that one out 🙄

the other thing is the AC breaker for the converter on?  

I'm with Bid_time. I'm betting on batteries. Have you checked your battery voltage? I know it's easy to assume that because you replaced them they are good and were charging. But that's an assumption. You may also want to the check your battery shut off switch. A surge from lighting strike could have damaged that. 

From what you are describing it sounds like your batteries are toast. You didn’t say if you checked the voltage directly at the battery terminals, of both batteries, while not connected to shore power, and what that reading was.

Same thing with the fuse panel, you didn’t say if you checked the voltage, while not connected to shore power, directly on the incoming  lines from the batteries.

If it’s not the batteries then start taking voltage readings at every junction box, switch, etc, from the batteries to the fuse panel. Yes there maybe a bad fuse somewhere in that main line between the batteries and fuse panel.