focus st170 immobiliser on constant when alarm set off?

Hi, my problem is i bought a new key casing and changed the internals over from the old key, after doing so i could not get key to let me in unless i put key in door, this sets alarm off and i had no way of switching it off with remote not working. I saw this site and promptly did the 4 turns in ignition and my fob now unlocks and locks but since alarm went off i just cant get engine to start! I get all the lights on the dash but no start