Formated modded 3ds, need help to reinstall apps

Hello ! I recently bought a 2ds, but received it already modded and without its sd card… I tried (stupidly) to reformat the console thinking it would set it back to normal (of course it didn’t work😭). The FBI app remained on the home screen, it’s the only app remaining. Now i don’t really know what to do : i’d like to reinstall some modded apps but i don’t know how to do it and I’m afraid of bricking it… I have my own sd card, i just don’t know what files to put on it or the process needed to reinstall those modded apps. Idk if it’s important but the luma 3ds version is the 12.0.1. P.S : would need an answer as quickly as possible, in the case I would need to send it back to the seller to get my money back (I only have 2 days)