RE: ESC caught on fire?
From what I see what you wrote and the pics, I agree with you that the esc ,,,, never mind let me type what I don't agree with. That is the only part I don't agree with is that the small arc you heard was an internal short. I think they all do that and the higher the voltage the more pronounced is the arc. So , I think your esc just went bad.
I have a few redbricks , but haven't tried them yet. They don't have the best reviews of course. What do you suppose your current was when WOT when it burnded up?