sorted this issue just by removing the bottom battery cover then removing the 8 or so screws that holds the base , as soon as you gently slip the bottom case off be careful as there is 2 tiny little ribbons that are pop fit 1 to the left top, 1 to the right top,also to the top right corner you will more then likely see the ribbon that has come out of its clip fit, gently lift the flap and re insert the ribbon and then re close the flip catch, this is such a common problem with the 3d ds as the ribbon is tight so it don't take a lot to dis lodge it, a slight knock or it being dropped, i hope this helps those that don't think they are able to attempt to fix this just take the dive it can't get no worse if it don't work in the 1st place ;0) and if you manage to fix it your be the best dad/mum in the world makes it worth trying don't it ? lol