That small crease can make all of the damage. If I was you, just get a maginifying glass, and see the crease zoomed in. If you can more or less see the ribbon looking like it's dettached from there, then yeah the ribbon might be damaged to the point of replacement. Oh, and yes, a ruptured flatwire WILL effect the speakers since they are connected together and they are connected to the mobo through that one ribbon. Sucks doesn't it? Anyway, at this point, you might need to get a replacement screen if you can't get the ribbon to work. The speakers enable sleep mode by triggering a smalll switch in the DS. It's a kind of reed switch so you won't really be able to notice it. Basically, all speakers have magnets, but these are placed here so that when the DS is closing, the magnets are over the ABXY, and under that area is where the switch is. You can get a strong rare earth magnet, and try to place it over the buttons, and if placed right, it will make your DS goto sleep w/o it being closed. It won't damage it so you can do it w/o any worry.
