LG 50PS3000 KEY LOCK

[EARLYBIRD]

Hi.We have a LG 50PS3000 in key lock mode,The customer said they were watching tv when it went of for 5 secs then came back on locked on channel 5 and you cannot change channels.The remote works but you cannot access all the menu functions.We have tried to go into service mode (pressing both menu buttons together) but it just comes up KEY LOCK.Anyone had this problem or know how to factory reset.Thanks earlybird.