Switch on TV with vol - /prog + pressed to access service mode. Chan + to scroll menu - stop at n v m - a red & a green 2 digit no. appears. Use vol + until green no.C5 changes to 5 Red display shows 00 for lock to be off. Change 01 to 00 using 0 button then sw off TV. (Location 4D may need changing from 01 to 00)