Topic: Corrupt save file on Smash 3DS??

Well, I know there's already a forum around here like this, but from what I've seen, i'm not having the same exact problem. See, what happened was that I started my copy of 3DS Sm4sh to play with a friend, but while booting up, it said it couldn't find an sd card. I think I turned off the system after this but when i turned the system back on and tried to play the game again, it would just go black as if it were booting up, but it doesn't show anything at all. No message about a corrupt save file, or a required update, nothing, just a black screen. And I also tried the game on my spare 3DS, but it worked fine on that one, so I'm assuming it's something within in the SD card. I also deleted the extra save data off my sd card through the system settings along with my dlc data to see if it would help, but nada. I know some of you might say it just takes a while to start Sm4sh because is a large game, but it usually only takes about thirty seconds on a regular 3DS, and when i was doing it, I was using a New 3DS XL, so it should've taken even less time to boot up. I've googled my problem, and nobody seems to have the same problem as me, so I could really use some help.