I tried that also, but still failed.
I tried to activate usbNetwork with auto loading, and it work, I can access the terminal.
So I guess the jailbreak is still intact but somehow cannot be removed or install new hack (I tried ss hack and it also failed)
Btw, I got jailbreak and usbNetwork folder from the zip files but I cannot find the LP folder in the zip file, as far as I remember there should be LP folder in kindle home folder. Probably this is one of the reason it cannot be uninstalled?
Can you please share the LP folder?