Hardware Need help with sd card for 3ds

[NicoAICP]

I got to Christmas a Samsung MicroSDXC 128GB EVO Plus UHS-I Grade 1 Class 10 .
Before i downgraded my 3ds i tried it and it doesn't work with my data.
I inserted it without any folders in it, started the 3ds and it worked.
Then I started the homebrew launcher (Freakyhax) and tried to install a game from fbi (and waithax).
When i started to install the game the 3ds said i ejected my sd and it reboots now.
My Question is how to use the sd without problems on my 3dsXL without loosing my data and how can I install games on it when it "ejects" itself?

 

[NicoAICP]

And what happens if it won'T start while i have arm9loaderhax? Will it brick or do i have to use a backup? because i don't want to install the 50GB of games again. (10GB are movies made with VCC13)

 

[KingofEquestria]

How do you convert movies