I installed a9lh OTPless on a 9.2 N3DS, downgraded from 9.9, the downgrade took two runs to complete, the first time I got an error that right before the last two files and my 3DS shut off, the second time I ran it it just installed the final two files and completed normally- otherwise, the otpless installation went incredibly smoothly, this was my real first time doing anything with a 3ds as I got rid of my old one, other than homebrew when it was FIRST announced.
I used browserhax as an entrypoint, and if it means anything, the n3ds was brand new, bought it the same day i got everything working.
Worst part is that I used my android phone to format/read the SD card since I didn't have an SD card reader, so not only was it formatted with whatever default method android uses, but it was also cluttered with default android directories and cache/database files, but everything worked fine