There is a pretty steep learning curve. It seems that as scanners progress, that learning curve is steeper. This is something that requires patience and practice to overcome. Most everyone has gone through this in the beginning.
When you connect your scanner to a computer using the supplied cable, you should see a message on the scanner screeni:
USB Cable Detected
Select USB Mode
Mass Storage = "E"
Serial Port = "."
Press the E Yes button. That puts the scanner in Mass Storage mode and the scanner acts like a removable drive on your computer. (You only have a few seconds to do that, otherwise the scanner goes into battery charging mode). The scanner should then say "USB Mass Storage" and cease to function as a scanner (because it is in "programming" mode).
From there, without Sentinel running, use your computer's Windows Explorer. You should see the scanner show up as another drive, mine says "USB Drive H".
Once you get that, then you can start Sentinel and do what you wish (update firmware, Master database, read/write Favorites Lists, etc.)
With this scanner acting as a USB removable drive, unlike all other Uniden scanners previous to the x36/Home Patrol line, there are no drivers to install to achieve scanner/somputer connection.
One thing that puzzles me is that you said you've updated the firmware. The only way I know of doing that is with the scanner connected to the computer. But you say you can't do that . . .
