Not many people change the default password for the USB port login because you have to be there to get into the VM. So, I'm guessing that you didn't install it or that you won't ever change it again.
The quickest way into the box is by doing a system initialize with the dip switches. I think there's a reset that doesn't clear the box, check the manual. If not, you probably know what the next step is: either Panasonic will have to reset it from remote, or you'll have to completely initialize it.
LkEErie