I have had an issue before with my 3ds with the exact issue here
https://gbatemp.net/threads/3ds-blue-light-flash-doesnt-boot-with-sd-card.466091/
I was able to fix it and update my 3ds from A9lh to boot9strap w/Godmode and the current Luma.
Recently, I was playing on my 3ds and put it into...