iveco 75E17 revved flat out and now wont start?

hi i have a 75E17 which had the turbo go last week and lost quite a bit of oil into the intercooler and exhaust manifold. i have today fitted a new turbo, and the iveco started first time beautifully. i left it ticking over for three or four minutes and all of a sudden it revved flat out on its own.. i tried to turn the key off and it wouldnt stop, so i put it into 5th and stalled it... now it wont start at all. any help please?