Green rust from water in the game slot.

You would need to get some contact friendly rust cleaner and a swab[q-tip] and clean it there. Then make sure no water gets down there.

even if the DS is off, if water gets on or in it at ANY point, power is still flowing if the battery is installed. Something probably shorted. I would suggest calling nintendo and asking them for advice; they are very lenient when it comes to this kind of stuff(in my experience). Also, i recommend yelling at your daughter for pouring water on your electronics, but only if she is old enough to know better. If she's a toddler, tell her "don't pour water on stuff." If she's a baby, just sigh and accept it as another part of parenting.

check the connector where you plug the game it maybe dirty or some pins broken

clean the connections in the slot with a lightly damp q tip. then dry it out with the other side of the q tip. maybe use a very light ( and i mean very light) amount of soap in the water. then clean with no soap in the water, then dry. and don't use it for 24-48 hours so its garanteed dry. this is how i get old nintendo's to work properly everytime. do the same thing to ur games so they don't put anymore dust into it. remove all water or connections may rust. make sure battery is removed.

you should have it looked at by a game shop like EB games and have it shipped for repair

I have fixed this several times and have had great results.

I take the back off, being careful not to break the very delicate power switch.
Then I take a cheap paint brush and 91% alcohol and gently rub behind the prongs until I have it all broke up and removed. Then I take a can of air and slowly dry the board off. I'm careful not to tip the can because then your spraying liquid air on the board and the extreme cold can damage the circuits.
it is a very delicate procedure, but I have had amazing results.
I'd be happy to do it for you

it may be a technical difficulty in the gba slot try bowing in it or get a q tip and kinda dust it out or blow in the game becuse the game isint making any connections to the ds and with the charger thing if u push in the charger too hard you might mess up the reciving thing inside the ds so it wont get the charge so be very careful when it comes to ds.....if u have any more questions plz let me know

before i answer how many times had you charged since you bought the ds

The DS Card Slot may be loose. If so, try not to touch the game card while playing.

Or, there may be a piece of dust or lint in the card slot. If you can see the lint, pick it out with clean tweezers. If you cannot see it, ask a mechanic to open the Ds and pick the dust out.

If you are referring to a game going out during game play you need to clean the DS game slot as well as clean the contacts on all your games. The games contacts get dirty, sometimes you can't even see the stuff building up. When you put the game in the DS that dirt transfers to the DS's connectors and they get dirty over and over again until they no longer make good contact with the game. This has been a cause for game lock-ups etc. ever since the first NES console in 1985. Purchase a cleaning kit from a local store like Game Stop or Wal-Mart. If you can't find one there try Ebay. DO NOT USE ALCOHOL, this will break down the gold plating on the game contacts and the DS contacts.