I think even though you formatted the device, it is still treated as a CFW device. If you are lucky you might be able to fix this by getting access to GodMode9 at least, in there you would basically have to mount the system NAND to the console and uninstall CFW, then after that you can proceed to format the device again and theoretically restore usage of different SD cards.
The uninstall guide can be found here:
https://3ds.hacks.guide/uninstall-cfw.html
One thing you can do to see if the system is still treated as a CFW device, make sure the files from before are present on the SD, insert the original SD card back into the console, and hold start to either access GodMode9 directly or Luma Chainloader (either way you should have already set the CFW device up to access GodMode9 one of the ways). If you can access it via holding start then fantastic, if not, do not fear, I have another idea up my sleeve.