Thermador oven circuit board troubleshooting - where to go from here?
The board isn't really a repair forum. But from an electronic design standpoint, when large components like relays are attached to a PCB, a potential weak spot is created due to thermal cycling, vibration, etc. An intermittent open circuit can be hard to diagnose because when you remove the board, you change the stresses on the component and PCB.  So carefully inspect the solder joints of the bake relay for cracks. Or, just resolder them by adding flux a little fresh solder while reheating them. They solder should be shiny and concave between the pin and the PCB trace. Also inspect the PCB traces using a bright light behind the board. Good luck!