It sounds like your nephew is shutting off mid game or when the game is being saved,it corrupts the data on the sd card and stops the card running properly,its something you have to teach them
Any friends or family that can allow you run the files,takes 2 minutes topsno i just have access to a dsi this is really bumming me out im getting withdrawl symptoms lol
If your dsi is 1.4.1 i should'nt think so,is there a game shop near you that you can try out a ds before you buy,have all the files ready on the card ready to update and be in and out as quick as you can,i am sure there is someone even a neighbour who would have one,nearly all households have a ds,or even a pawn shop,tell them your going to try it first