[Help] Helping a wet DS Lite.

Assuming that it was turned off when it was soaked, you should have immediately removed the battery and placed it somewhere warm so it can dry, preferably with the outer casing removed. You must leave it for at least 72 hours, or longer if you can't remove the case, before even attempting to switch it on. Water, or any other non-sweet beverage for that matter, doesn't kill electronics that are off; it will only do so when the device is powered. I think if you didn't try and turn the DS on after you spilled water on it, it would probably still be alive today.

I've managed to submerge a mobile phone under water, and fortunately it wasn't on; it still lives on today.

Jam it back in, in the dark.