Kenwood KVT-617DVD

I just bought a Tahoe from a car lot and a Kenwood KVT-617DVD was installed. When i turn it on it is asking for a password the people i bought the truck from said it was like that when it came in and they didnt know the code. Does anyone know if there is a master reset code or how i can get the code? I was told I could pull the casing apart and there would be a 4 digit number inside but there wasnt. Any help would be great thanks.

Your radio will require one of the following procedures.

1-During the code request mode, while holding the DISP key depressed, press and hold the Volume UP or DOWN key for 3 seconds (so that

Thanks man thats what i had to work with to but didnt work i found a place local that will reset it for $50 think im just gona do that.