Sounds like it was modded a good while ago before Luma hit the scene. Check what CFW you already have installed: https://3ds.hacks.guide/checking-for-cfw.html Make sure to check whether there are any NAND backups on the SD card or if the previous owner sent you a backup somehow. It may be necessary.
https://3ds.hacks.guide/checking-for-cfw.html
Make sure to check whether there are any NAND backups on the SD card or if the previous owner sent you a backup somehow. It may be necessary.