I will assume you are either on 4.x or 9.x sysnand. If not, consider upgrading/downgrading via
sysupdater. You should find a folder of (copyrighted) .cias for the update from [the website for "iso" and "3ds" files], which you should put in the "updates" folder on the SD card's root, then run while in RxTools 2.5 DevMode (NOT RxMode Sysnand. This will brick your 3DS if you even try to do that) Also, for whatever reason, DevMode was temporarily removed in 2.6.
Delete (well, I suppose renaming is safer) your "rxtools" folder on your SD card root (the very top folder of your SD card, right after "My Computer"). Also, delete "firmware.bin" from the root directory if you have one and make sure that you have "slot0x25keyx.bin" in the root. I can't link that file because it's copyrighted material, but if you google for it you should be able to find it fast.
Then, install
Python 2.7.x onto your computer and go to
https://lavanoid.github.io/ and download the latest firmware. It should link you to a Dropbox, so download the bottom-most .zip on the page (double-check the last-modified date to ensure it is the latest version)
Extract the .zip, then go inside the "release". Copy the "rxtools" folder to your SD card root, then enter the "Tools" folder and double-click "cdn_firm.py". It should generate a folder named "firm", which you should put in the SD card's rxtools folder you just copied over. (SD:/rxtools/firm/<3 .bin files it generated>)
If you have a DS mode flashcart:
Enter the .zip's "release/mset" folder and move the .nds file over to your DS flashcart. Run the software in DS mode and it will ask which ROP (ds profile) exploit you want to install:
If you are on 9.x sysnand with downgraded 4.x MSET: Select "4.x DG"
If you are on 4.x sysnand: Select "4.x NDG" (I think? Otherwise keep trying them all and see which one hacks ds profile for you...)
Otherwise, do the web browser method:
Enter the .zip's "release/mset" folder and move the .bin file over to your 3DS SD card. Put the SD card back in your 3DS and go to your web browser. Turn off your wifi and go to "
http://dukesrg.github.io/?rxinstaller.bin". Close the web-browser, reboot, turn on wifi, and re-enter the web browser. You should hopefully get a browser crash, which you should go to DS profile after that.
If the ds profile exploit still doesn't work, try deleting your history/bookmarks/cache from your 3DS web browser and try again.
After you got ROP installed for MSET:
After you run rxtools (or hold R to mess with whatever you need to in the menu) then you should be booted into EmuNAND. From there, go to system settings,
double-check that your firmware says something RXTools-related, then perform a system update within system settings in emunand and you're done. Like most versions, you will boot back into SysNAND if you exit System Settings.
Finally, if you accidentally download update software on SysNAND, just hold L+R+Up+A while powering on your 3DS, then cancel the system update and it should delete it from your system.
Oh yeah extra note. homemenuhax can be faster/more convenient than going through system settings>ds profile. If you are on 9.0~9.2, consider installing it via this guide:
https://gbatemp.net/threads/rxtools...rom-browserhax-homemenuhax-to-rxtools.398420/
