I'm sorry that you have not received a knowledgeable reply. It will take someone with very specific knowledge, I think.
It's a very long shot, because getting a defective part happens, but not often, but put a propane
torch to the flame sensor and see that the resistance changes.
What does customer support say about the five flashes? Is that a coded error?
Is there voltage coming to the flame sensor?
Sorry I can't do better.