Viking Range ovens and griddle will light then shut off

I have a Viking VGCC548-6gss built approx. 3 yrs ago. I have converted the range from NG to LP as well as installed new regulator. All 6 burners work and have always worked. Originally the small oven and griddle worked while the big oven did not (not sure about the broiler.) I swapped the small oven’s DSI with the big oven’s and the big oven turned on (but did not stay lit.) So, I replaced the big oven’s DSI. Now, both ovens, griddle, and broiler will light but shut off within 5-10 seconds. What is my next step, here? Is this a control board/motherboard issue? The ovens/broiler/griddle have gas coming to them and they are all lighting but not staying lit. I can’t believe that ALL the heat sensors are bad, so that leaves something else electrical - but what?