Panasonic radio code not working after sitting for a 1yr

This is BS. I have a Panasonic CQ-VD6505U unit. I assigned it a code when I first installed it in my truck. I even wrote it down in my manual. It's been sitting for about a year and a half and I just bought a new truck and thought I would install it today.

When I powered the unit up I eneterd my 4 digit code and it says it's INVALID
How is that possible I set the code myself and wrote it down in my book.

Anybody have any advice for me? I can take pics of my unit and manuals to show it's not a stolen unit. I bought this back in 06. Does the radio have an internal battery that I can reset? I heard in other countries they have consumer laws that don't allow a lost code to BRICK a unit. Id be fine with paying to have it fixed. This sucks.

 

I got it all resolved. Panasonic will not help you out. Unless you can provide proff of purchase. I got is as a B-day gift 4yrs ago....good luck with that one. It took 2.5hrs of looking on the I-net till I was able to find a way to reset the code. Was a real chore to find the limited info on that unit. I'll leave it like that so theives cannot see how to reset it. But for the record it is possible. I did it.