Panasonic CQ-DV7500U ID Code problem

I own a Panasonic In-Dash DVD player, which I set the code to when I installed it. The problem however is that there is no way to enter the code when the power is reapplied to the unit (car battery died). I looked at the manual and it says to enter the pin, but fails to mention how. The obvious methods, the remote, or buttons (no #'s) on the unit itself fail to do anything. I have tried contacting Panasonic several times, and emails, but they have been utterly worthless, which btw brings me to my next point. Dont buy Panasonic.

Yea, unfortunately the HU itself does not have any radio buttons on it, not many buttons period for that matter. I am hoping I am missing something but the manual has netted no help, and talking to panasonic hasnt either. Its a pretty stupid design IMO, because you use the touch screen (displaying the digits on the screen to set it) but to enter it for verifcation (like my case) the unit does not display any #s. Its been weeks and neither myself, or anyone else I have driven with has been able to figure it out.