I have an old Hitachi not your model# but this worked for me. Have your t.v. on even if it is sound only. Use your hitachi remote . If the key number has been forgotten perform the following procedure to release the child lock access code.
select menu use the + or - button to select child lock. Press menu button select key number change using the + or - buttons.
Press the menu button and enter old number as well as 000 will be displayed on the screen. Select 7 by using the + or - buttons and then press the menu button. Select 7 for all three digits of the access code. In other words the 000 become 777
Enter new number and 000 will be displayed on the screen. Press Menu button 3 times to keep the defaultkey number 000
The display will change to new key number entered
Select child lock cancel using + or - button
Press menu button Enter key number and 000 will appear on screen
Press Menu button three times to enter 000
Child lock is now released and the broadcast picture will be displayed.
On my tv I had to hit end for the picture to show
kathy, August 2009
