Either way, you're fine. The tough ones are the little ones.
This is the guide I used:
https://gbatemp.net/threads/tutorial-noob-friendly-nand-dumping-2ds-3ds-3ds-xl-n3ds-n3ds-xl.414498/
I recommend only doing a temporary hardmod so you don't have to worry about making holes and buying connectors.
what do you mean temporary? Does that mean I have to redo it?
And says new! nintendo 3DS so it must be new kind.