I rarely use the sleep mode fuction on my DS, and if I do the sound is off. Today I was playing NSMB and put it into sleep mode, but this time the sound was on. I could still hear sounds of "Goodbye!" "It'sa me Mario!" repeatedly emitting from it. It checked to see if anything was wrong with it and sure enough if I held it slightly open I could see the screen flicking on and off when it should have just remained off. I investigated to see if it was my game cartridge, or my DS. My friend put in ym NSMB cartridge, went to sleep just fine. So I then checked if was only my DS and it was.
So my question is, it seems to be closing fine, so is the problem probably with the hinge or within the DS itself?