You need to enter the setup menu to access Child Lock.
I doubt that is your problem.
Factory reset is also via setup.
I assume you have tried seperating the appliance from mains for a few minutes.
Did you try removing the batteries from the remote, press a button to discharge any capas and then put them back in again?
Call their helpline:
1300 726 642
If they have a secret key combination to reset the player, please post it here.