Fixing a backwards brushless motor is easy-peasy. Switching any two wires of the three wires will reverse the motor’s direction. Really. It doesn’t matter which ones.
How can this be? Imagine that each wire is numbered. The speed controller is pulsing them in turn: 1-2-3 1-2-3 1-2-3… and so on forever.
But your motor is running backwards. It’s going 3-2-1 3-2-1-… instead.
If you switch the first two wires (#3 and #2), 3-2-1 becomes 2-3-1. Run that for a while and you get 2-3 1-2-3 1-2-3, which is just what you want.
If you switch the second two wires (#2 and #1), you now have 3-1-2. Run that out and you get 3 1-2-3 1-2-3 1-2-3 which, again, is just what you want.
First and third wires? Same thing.