How and where to download the firmware fora cisco m10 valet?

ive recently bought one of these and i have my xbox 360 hardwared to it and it is completly impossible to open the nat. ive tried every singe way including shutting down the firewall all together. the only other option is to download a new firmware that might get it working and ive never done this before. could someone please give my a link to the firmware update and or tell me how to do it.