steering colum motor change

I had a faulty steering colum motor on my 54 plate scenic, so ive bought a second hand one from good scrap merchant, mechanic fitted it and started the car and moved it 200 yards, locked it up, when I came to pick it up the car now wont start or turn over and the fault notice on the dash is saying that the steering lock is on then off, also when the mechanic links in his diagnostic computer its not recognising it,,, can any one help me understand what might have happened and any remedies

manythanks

jezza

steering colum motor change