[Workaround] Boot nds firmware

[askotx]

Steps to boot nds firmware:

-Required files: bios7.bin, bios9.bin, firmware.bin in retroarch [system] folder
-Run any nds game.
-Call menu (F1 on PC, Guide button Xbox, Start+Select, etc)
-Go to [Quick Menu] -> Core Options -> Boot game directly -> [yes]
-Next go to [Close content]
-Restart that nds or any other nds game, it should boot into NDS bios/firmware
-Make any change you want on BIOS: Change username, Language, Birthday, etc
-[Turn off NDS] from firmware
-Call menu again
-Next, go to [Quick Menu] -> Core Options -> Boot game directly -> [No]
-Next go to [Quit Retroarch]
*IMPORTANT: Delete previous saved game files [Gamename.sav] from melonDS folder, if you want to reflect any change on language, in my case
-Boot/Start that game with new firmware options, it should be display updated language, username, etc

Taken some help from: https://www.youtube.com/watch?v=1q2fY7P_Xmk