Depending on which "frame board" you are talking about, my experience may help. The narrow strip of plywood that support the trunk lid hinge fell out on my A122s. I tried the dealer but couldn't get a "fix while you wait" appointment. (You call them in the morning and they give you a time that day, if it is slow.)
To solve the problem, I removed the hinge bolts, replaced the plywood strip and screwed it into the plywood behind it with an appropriate length deck screw. I replaced the bolts and haven't thought of it since.
If you are getting water in the trunk, the dealer should be able to fix that under warranty. But it might help to get your own idea for where the water is getting in. The most likely candidates are the trunk lid or the baggage doors. If you have an adventurous small person around, put them in there with a flashlight and spray water on the front of the camper, as if it were raining. Even if you discover the leak, I would keep that information to myself and ask the dealer for a complete leak test to see if they can find any additional points of entry.
2012 Rockwood A122S
2008 Toyota Tundra Double Cab 4X4
Former owner of a 2002 Coleman Niagara GTE