If you don't have a controller, just on/off switch for your hydronic heater an EasyStart Select could be the least expensive option to retrieve codes and cancel lockout mode.
I have EasyStart Timer controlling both Espar Hydronic and Airtronics heaters able to retrieve codes from both. Adding a Timer vs Select would give you timing option. https://www.heatso.com/espar-eberspa...ronic-heaters/
Eberspacher Hydronics could be operated with a simple switch, your camper is likely wired that way. Adding a permanently wired EasyStart code retrieving unit could make life easier even if you choose someone else to do work you would know your starting point, perhaps not Winnebago recommended screen replacement.
If your son had low fuel in the tank and the heater's fuel pump suck air the heater would fail to ignite, 5 times no ignition would give you a lockout. Fill the tank to over 1/4 full and cancel lockout is likely all you need.