Possibly procedure described in FIXYA question below will allow you to reset the pin.
This is the definitive answer from Panasonic Customer Services. It worked for me.
In response to your enquiry, I am writing to inform you that you can reset the PIN number to the default 0000 and then change it, based on your preference. In order to reset the PIN, please follow the next steps:
1. Switch ON the unit;
2. Press and hold the OK, YELLOW and BLUE buttons, at the same time, until you see 00 RET displayed on the unit;
3. Press, repeatedly, the RIGHT ARROW buton until you see 03 VL;
4. Press OK and you should see "INIT" displayed on the unit.
This will reset the PIN number to the 0000 factory preset.
Furthermore, you should also be able to remove the message that is asking you for the child lock PIN while attempting to play back a recording. In order to do this, please follow the next steps:
1. Press SETUP;
2. Choose HDD/USB HDD;
3. Select CHILD LOCK FOR PLAYBACK;
4. Input the default 0000 code;
5. Switch it to OFF.
After performing these steps, the recorder should no longer ask you for the PIN when trying to playback a recording.
I trust that the above information will be of assistance to you. However, of course, if you should have any further queries, please do not hesitate to contact us.
Customer Service Team