Guys when looking at the beam don’t assume the fire or the vehicle cause it to be in it’s current position. If you watch the video the fireman were on the roof with chain saws opening up to get water on the fire. They may have cut the beam.
Sure looks charred and burnt through to me on the right hand side in the second picture in 463...
I believe you’re probably right about the garage door header being pulled down by the firemen. I don’t think they did it by cutting through the roof as the header would have been attached to the front wall but it was flaming and they would have wanted to pull it away from the masonry and douse it. The garage door would have been attached to it so it may have simply come down when they were pulling down the flaming pieces of the door if it were in the open position.