Where would I find info on upgrading the firmware on my standalong player?

I have a sony DVP-NS700P. It works fine on playing just about any media, until today. The thing is, that this player has a problem with the audio in this "standard" dvd. (it may not be standard). The strange thing is that my other player, the same make and model, plays the disk.

I checked how it plays other disks and I am sure there is nothing technically wrong with the deck at least as far as I can say. The disk which was I found this issue, does not have standardized audio, and I bet it is having some trouble with this.

So I wonder if sony has a updated firmware for this player? Can you upgrade standalone players like PC based units?

Where is the place to find stand alone player firmware/upgrade?

THANKS!