On one old set (can not remember the make, model) I removed the back up
battery
Once I even took out the EEPROM and saved it to computer file, cleared it,
then put the EEPROM back, I think from memory it worked.
Is that on the VCR or the remote?
My Sharp VCR unlocks when the play button is kept depressed for 5
or more seconds
Sorry. I have to correct my earlier reply.
I went to test your question and found out, that my Sharp does
not unlock on '5 seconds play'. (Akai will though
Sharp has a 'key'-key on the remote control only.
The manual says, that pulling the mains plug for an hour or two
will reset the child lock.