Note: For those that followed my tutorial on installing BrowserHax and Downgrading to v9.2 here, you can simply start from Part 3 from Plailect's guide to setup RedNAND and downgrade to v2.1 for arm9loaderhax for your 3DS console. Although it is a long winded instructions, your effort will be rewarded in the long run. Just be sure to follow each and every instructions carefully during the process.
From there onwards you can always update your arm9loaderhax patched sysNAND to the latest version without ever worrying about bricking your 3DS console! That is only valid if you use CFW such as Luma3DS which will have write protection against FIRM0 and FIRM1 file on your sysNAND. Gateway mode does not ensure this! So never attempt to update your software when you're booting into Gateway mode via a9lh.