Final update:
After 3 internal fires and 2 failed complete Truma units, and a request for a Truma Escalation, the company (Truma) stepped up and replaced our whole water heater unit and external (kinda warped/melted) door under a "warranty exception" after finding another problem in the unit during testing of the new Recall burner.
That make the 3rd Truma water heater installed in our hull. This one now is fully registered and has a 1 year warranty.
Hope this one is the last we need to install.
Craig (Hull 505 - aka Galway Girl)