if you have never soldered before i suggest you look around for someone to do it for you and save the cost of soldering iron etc, because if you mess it up and burn the pads off or anything you will be stuck on your updated nand then or even worse a broke 3ds
even though you said you haven't found anyone to do it for you, you don't need to look for people who specifically fixes 3ds's ask in mobile phone repair shops etc, you should be able to find someone who can solder and already has the equipment at hand just explain its only 4 solder points and quite easy for someone who has soldering knowlage
That's the problem. Here in Brazil it's so difficult to find someone that has the courage to do such thing. Yesterday i've spent the whole day looking for someone that could just solder the 4 points and none of them wanted to do it. I think i'm gonna look for someone in my engineering college and see if someone can help me, otherwise i will do it myself.