Dude, this thread was so painful to read that I signed up just to reply to your question. I was looking for newer firmware for my AVC796B too...
You can find it here among a bunch of others: http://www.ussscctv.com/technical_supports.htm
The one you want is this one:
CPD556BD/CPD556B AVC796BD/AVC796B
v.1020
CPD556BD_1020.zip
13.2 MB