fabia vrs steering angle sensor

hi my friends just replaced the gearbox on my 2005 fabia vrs. As soon as i got in it and drove the esp light came on and the breaks locked on and the esp light started flashing. I drove off again and it was ok but the light stayed on and does not turn off when i press the esp button. ive had the code read and it says steering angle sensor. Could my mate of knocked it or do i just need to get a new sensor? when i start the car the light does not come on its just as soon as i move it comes on and the brakes occasionally come on