Hello,
I know this question is old, but for the purposes of suppluing an answer for others who might have a simmilar issue, that is condensation between the LCD screen and the plastic layer of the upper display. You can get the [guide|3877|screen off], and clean off the condensation using a micro-fiber cloth. Although if you believe the DS is water damaged then you should problibly check out some of the tips on the [guide|95280|iPhone Liquid Damage Repair Guide], as the tips should still be useful.