How to actually update to any system software version (more or less) properly:You can update your 3DS to 9.2 using a game rom or CIAs. But you can't do it to sysnand directly or it will get bricked. Karl3DS will probably allow doing this safely. But until then, you'll have to copy sysnand to emunand and update emunand to 9.2 using CIAs or a game rom with the 9.2 update. Then you have to use rxTools to inject the firm0.bin/firm1.bin files dumped from an already working 9.2 sysnand image. If you never had 9.2 on your 3DS, this means getting these files from some one else. (also note that they should have "emu_" added to the file name so that rxTools will see them)
Once you inject the working firm0/firm1 files into emunand, it's then safe to extract emunand and flash that to your sysnand using gateway menu. While it shouldn't cause issues, I still recommend you get a hard mod if you are in any doubt on if you did it correctly.
Generally, if emunand boots correctly afterwords, you can have it on sysnand once the firm0/firm1 partitions are fixed.
Also if you go the CIA route. You can selectively leave out the CIAs for TWL_FIRM and the DS Cart White list. That way, whatever DS flashcarts that are working on your current sysnand will still work on 9.2.
For example. If you started out with 4.3 FW on a USA console updating to 9.2 in this way would allow AceKard2i to still work. Gateway blue card will still work if you updated from 4.5. I don't recall exactly when that one was blocked. But you get the general idea.
1) Install all the CIAs for the updated version you want
2) Call AM:InstallFIRM to actually install the FIRM titles that updated.
(even better would be returning a spoofed response to NIM and having the system updater put you on 9.2)
Sounded like "people updating the N3DS with cards, causes bricks"... I guess I didn't read all the comments that you previously wrote... Well, least I know now 
