I may be missing something but what happens when you don't have a rating in a skill you're trying to use?
No skill = check for another in the same field. If still none, you just get no dice there.
If you can't get any dice for a roll, from wherever, you don't roll any. No augments gained, no dangers cancelled.
The Guide shouldn't generally be calling for a roll at all in those circumstances, of course, but if the flow of play gets you there (a player going "I try that too!"), there it is.