how to fix key pad problem on 1997 peugeot 406?

hi Please can anyone help
driving back from MOT after fitting new engine my 406 just stopped and would not restart
when numbers tapped into key pad both green and red lights came on tried again but same thing happens
spoke to local dealer who says its because we have used an emergancy code for more than 1000 times we have used same code since buying the car 5years ago second hand from them
and we were not told that we had to alter the code in fact we wanted to but their sales person could not alter it so said to leave it as it was
any advise on how to fix this problem or bypass keypad very greatfully received as my mechanic is totally fed up having just got the engine in and MOT done
please email cavydover07@ntlworld with any suggestions

many thanks

maggie