There is no such thing as "Scratch X did not work". It's a degree of how much it can take out.
Especially on damage like that where I'm sure you have many varying depth scratches.
I've never seen it not seriously improve things, which is what you asked for.
If it was one deep scratch, sure you could say, it didn't work. But you have vary scratches there and it should take out all the shallow ones, maybe not the deepest ones. There is no way that is all deep and out of reach.
If you really did use Scratch X (with some serious elbow grease) you would not be saying, I could cause $500.00 damage with it, because that is extremely hard to do because it's so mild and forgiving.
If you just babied it and wiped it on and wiped it off, yes it won't do anything.
Orbital is ideal, actually better than by hand because it's very even, easier to do and also pretty hard to mess up with Scratch X.
It is much better to polish the clear coat than fill the clear coat with paint.
Note: This won't be your last scratch.