The problem that I had before is sorted. Although now I'm stuck again.
I've managed to manually calibrate the ESC's, although now this issue is that I can't arm the APM, the red light flashes, I push the throttle down and to the left, hold it there for over 4 seconds and nothing.
However, if I push the throttle up and to the right the red light turns solid, I've reversed the throttle on the TX but it still arms in the same way.
Once the red light stays solid and I move the throttle, nothing happens.