kid addicted to Nintendo DS

Put some time limits on it. X hours a day. Grant him an extra hour a week for doing chores or getting good marks, or whatever you chose.

This is not a tecnology issue, it is a parenting issue, and it won't be a tech solution.

is to rub some water on the battery contacts regularly. They should eventually rust. You might also install batteries that are corroded to the point of leakage; the acid should corrode the contacts. You might also try rubbing water on the contacts where the game modules connect, on both the DS and the games.

You're not solving the problem by degrading the hardware. There's nothing to prevent the kid from buying another one, and then you're back to Square One. Unless there are diagnosed psychological problems, assert your parental authority. You've turned off the Internet; how is this different?

Seriously, sabotage is not the answer. If you cannot control them when they are ten, heaven help you when they hit fifteen.

The correct substitute activity depends on the age. There are TONS of other things to do:

a) get him/her a green screen and a cheap digital camera, and install some movie-making software. Make movies. LOTs of fun can be had with stop-action software, making lego or play-dough stop action, etc.

b) snap-circuits, connectix, or similar building toys.

c) educational software

d) family together time: family game night, one-on-one time, no-electronics-day, home power-off day, indoor camping day, etc.

e) use the video games as currency (see chore-piggy app). Lock up the nintendo stuff and only grant access based on chores done, good grades, good behavior.