How do you replace on and off switch Nintendo ds lite?

First you have to open the case. For this you will need a tri-wing screwdriver (widely available on Ebay).There are many instruction sites on the web to assist you here. Take the battery out first.

Make sure you have an anti static wrist band though, or you may short out the motherboard and then the whole process would be wasted !

Be careful when opening the base as the tow shoulder buttons will spring up and you may lose the small springs.

Once open, you will see the switch on the edge of the motherboard. The switch will requrie to be de-soldered from the motherboard (again not for the faint hearted). Again you risk shorting the board if you are the clumsy type. The new switch itself is easily obtainable from Ebay for around £5 ($10).

Simply re-solder the new switch and re-assemble case.