After 4 visits back to dealer and 5 months of problems keeping this new hot water heater going my dealer finally noticed it came without the flame diffuser from Dometic at the end of the burner. Once installed, works great. The new ones either have a diffuser pressed into the tube or a round circle at the end of the burner tube.
Dometic was horrible to deal with, average hold time is 50 minutes or more and they just tell you have your dealer call as it's under warranty.
I did learn lots about this product and hope I don't need it again in the future!!!!