Hacking backup and restoration of flashcard r4

[Laytonesto]

I have 2 r4 one works and another not because of a flashcard update error.

I would like to repair it using a functional r4, and trying with

-ntrboot (Failed to restore)
-GoodModo9 being Super User does not let me modify the files of the flashcard,

I need help if someone knows the way to achieve it.