The manufacturer says it's likely water damage caused by a leak from the outside due to improperly maintained seals, which is the dealer's responsibility. That's why they've denied the warranty claim. However, that still doesn't adequately explain the speed at which this damage occurred - a mere 2-3 weeks! That's why I'm thinking it might be an electric short as well.
Bottom line is that the dealer and manufacturer disagree on who is responsible. However, they both have agreed to fix the problem at no cost to me if I bring it to them. So the dealer is going to have a go at it first, because they are local. If it resurfaces I'll take it to the manufacturer though they are 2000 miles away.
This is becoming a PIA. I didn't expect this on a new camper. But I really want to address this problem right away before it becomes a huge can of worms.
Thanks all for you input.