Try to start usbnet again, and then try to connect to it.
If you cannot connect to it, on your home page search put this in the search box, ';dm' to dump message.
Look in those files that get created to see if there are any errors that need to be fixed.
for connecting to a wifi hotspot with no internet, there is a flag. Make a file with exactly this name
and put it on the usb storage.
Then reboot the kindle to have it take effect.