As far as getting to the service menu.
I have "Sara" software on my SA8300HD box from TWC. On mine, to get to the diagnostic menu, I press and hold the little button that is in the center of the channel and volume buttons on the front of the set-top-box. On mine, it has a small "+" on it.
After holding it depressed for a few seconds the e-mail LED on the front of the unit will start to flash. While the e-mail LED is flashing, press the "Info" button on the front of the box. The diagnostic menu will appear. Once it is visible, pressing the "+" one or more times will make the diagnostic menu translucent so you can still see the program behind it.
Use the volume up/down to go through the various diagnostic pages, use the
"Exit" button to return to your normal viewing mode.