Note that USBNetwork in itself won't help you if the main system is screwed.
The Rescue Pack (and its buddy, the Coward's Rescue Pack), on the other hand, will

. Because, in your scenario, you'd only have had to ask the diags system to start USBNetwork, and you'd have a had shiny SSH access in diags

. (USBNetwork, on the other hand, provides SSH access to the main system, the one that gets routinely screwed over^W^W
improved by Amazon updates

.