hi i have a problem with my radio,i have a program for ford codes which i put the serial number of my unit in,it gave me a 4 digit code which i have tried several times,and now the thing has shut down and wont accept anything,i think this unit has been recoded in the past,does anyone know how i can put the original ford code into the unit,ihave read my ford radio hand book and it tells me to leave the ignition in position 1 for 30 mins and the unit will accept code again.many thanks davo t ravo