Crescita-I use Cerama Bryte with the yellow scrubby thing.
This spot is not a burn mark or anything like that. It's a faded mark that looks like water/steam got on the burner and faded it. You can only see it at an angle but not if you look directly at it.
I might use the Barkeepers Friend because I see a lot of people using it on their flat tops. I have the dark black surface and the smallest things show up.
It's driving me insane!