Hmmmm , What ESC ( could it be faulty ? ) Have you tried another ESC ? ( To confirm or deny )
Battery , is it rated high enough ?
How was the ESC calibrated ? ( Servo tester ? ) Does the ESC require a program card ?
I had a 40A esc in one of my helicopters that never performed , even the cheapest Chinese 40A esc would kick it to the curb ..
I ended up putting it in the rubbish . ( I ordered 2 of them at the time , the other is still un used in my spare parts box , it could be rubbish as well )