I had a similar problem with my brand new Windsport 32N. Although with some difference.
I had my unit for a day or 2 and went to start the engine. Zip, zilch, nada. Not even enough juice to turn on the dash lights. Tried the emergency start but that didn't help. Finally put the charger on the battery and the engine fired right up. Didn't even have to wait for a little charge to run into the battery.
We went camping that day. Arrived at the campground and set up. I let the unit sit for a couple of hours and tried to start it again but it was as dead as a doornail . Being a little ticked off, I said "I'm going golfing" and off I went.
Came back after the round and tried again and it fired right up! Now what, lol. Did this several times over the next couple of days. Sometimes it would act as though it was completely dead and 5 minutes later it would start. Something else to add to the list of my wonderful
Thor.
Called the dealership and they had no explanation. After the weekend I took it back to the dealer to have the 28 items that I had found wrong over the weekend to get fixed. They said they couldn't duplicate the problem but thought the battery was probably the culprit. They replaced it.
That was in May but so far I've only had the motorhome back for 4 days in total. (It's at the dealership now and has been there for the past 9 weeks again) So, I can't really say if the battery replacement fixed the problem or not. The few days that I had it back it seemed to work ok.