Thanks for the suggestions guys!
The trouble-shooting I've checked was peppered with suggestions about corroded terminals. As I said the unit is less than a year old and very clean but I have removed/replaced all the "spade" terminals and I will check the burner connections before proceeding. My first thought on my return was the gas but I've cooked a curry since and it's all going strong.
btw, I've also fired up the Suburban NT 30 furnace to confirm that the 12 volt
amperage and the gas pressure are fine.
As I've said, the unit seems dead. I've checked the connections with the power on but there's not a hint of arcing except from the fuse on the board.