Why can't my 3ds xl detect my micro sd card?

I bought this 3ds xl from amazon but Nintendo’s page on amazon and while the rest of the system works perfectly fine, my system will NOT detect my micro sd card. I’ve tried pretty much everything and i can’t send in my 3ds to get fixed by Nintendo for some reason. I know someone is most likely going to berate me for buying a system from Amazon but i’m not here to get a lecture. I just need to know if someone else had this problem or if someone knows where i can get my 3ds fixed at. Thank you.