potterton supremer 401 boiler ?

heating engineer fitted two heat controllers to my boiler it seamed to do the trick for a week but fault came back .Green led flashes it clicks red led comes on for about 30 sec green led carries on flashing boiler dose not come on.The only way to start it is to switch mains on off,it will start on its own when it fills like it.The heat controllers was a screwing and a clip in