My previous set up was just a formated 3DS, i bought one and hacked it.1) Regarding the 022 2634 error:
https://www.reddit.com/r/3dshacks/comments/40qdwo/error_code_0222634_whenever_i_try_to_access_the/
system formate usually do the trick in removing said error.
2) regarding Nand back up: That done in the Decrypt9 part of the guide.
https://plailect.github.io/Guide/decrypt9-(homebrew-launcher)
What was your previous set up btw?
Still in the proccess of a9lh myself but I know some bits.
I need to backup my saves, does the system formatting process in the first link backs up my saves?
Also is it safe for me to update de system? My 3ds keeps asking me to update for a few days now