My brother in law is an electrician and sent me these today from a panel he’s having to change out for obvious reasons… He thinks the bus bars shortened out and the main breaker didn’t trip since you can see the breaker is still in the on position. Luckily the fire department put out the fire before it got to the house. He also sent me some photos from a four point done a year ago. From the four point pictures you can kind of see the bus bar is a little burnt at the top near the main breaker.
Interesting. Thanks for sharing.