Found Combi Oven unit not turning on, checked 5p ensure no a,p draw when powered supplied to unit found okay. Found hi limit for generator was tripped and could not be reset, found end of cap tube showed signs of being burnt or shorted out, believe tube was shorted out causing un-resetable damage to hi limit. Will order new hi limit for generator, outboard hi limit and return to replace. 8/8/19 Removed the faulty high limit and installed new. Then checked operation and the unit was calling for descaling. I pulled the water level probe and it was clean and nothing was grounded. I had some issues getting into the service manual because the dip switches were corroded. I tried resetting the descaler mode since we already descaled it but it wouldn't work. I checked the drain pump operation and it was fine. I called Rational and they had me check a few other things and found the water level probe wasn't sensing at all. I shut the unit down and water off. We will need to order parts and re