I'll agree with what most of the other people above have said. Moving to A9LH & another cfw is the right move. It's unfortunate but rxtools has fallen behind on the cfw scene so until it catches up you will be better going with one of the other cfws now available
The original CDN to 3DS didn't dump demo's in .3ds format, it only dumped in .cia format.
To get it to dump a .3ds of a demo the .py script needs to be modified so it dumps the .3ds as well. I'm not on my PC atm so I can't share the one I have but the one you have from Chaos may do it...
Try installing it again, it should install fine this time, after the failed overwrite it usually installs fine
Edit : like everyone said above make sure 100% you are installing to nand,
I have the correct patches installed, dsiware of the correct region works but dsiware I have made region free using the guide on here don't. I haven't tried the 3.9 update yet but hopefully @Aurora Wright was able to fix the problem. Region free cia's work so I would've thought region free...
@Aurora Wright (or anyone) should region free DSiWare cia work with AuReiNand? I have the latest commit I compiled today & the region free dsiware cia I made today isn't working, black screen & I have to reboot my console
Like Biff627 said above downgrading isn't a problem now whatever firmware you are on. The firmware you need to aim for is 9.2, once there you will be able to run a CFW like AuReiNand/rxtools etc. Buying a flashcard like Gateway isn't required
Gotta love Mr Burns, you should post your splash screens here for others to enjoy - https://gbatemp.net/threads/reinand-3-0-custom-splash-screens-thread.410948/
You can, hold L during start up to boot into 9.0-9.2 sysNAND with sigs patched then install this cia by @Columbo2811
https://gbatemp.net/threads/release-hb-launcher-mod-cia-for-gateway.416449 You can use that to boot into GW, it works fine for me
Try a different cia installer, bigbluemenu is old & outdated now & does throw out errors sometimes. Get the latest version of devmenu which is 11.4, you can find it in the homebrew section on the Chaos site
Thanks to everyone who has contributed the new entries, hopefully we can get those added in after the file is sorted out. For now until we get it sorted you can either use the link from the Chaos site by Jimmsu or the latest update in the 1st post