Alright so long story short my little brother brings home this DS that some kid gave him for free on the bus and it doesn't turn on. I have switched the battery with a known working one and it still doesn't work. I have also put the battery from the broken DS into a working one and it works so I don't think that it is the battery. When you plug the charger into the DS the orange light comes on like it's charging, but if you flick the power switch it does nothing. I was kind of hoping to come out of this with an easy fix and a free working ds so any kind of help is appreciated. Thanks!
If it does nothing at all (does not flash the green LED or turn it on) then it is usually fuse F2 inside the DS - to get to it you will need a tri wing screwdriver and take the bottom of the DS apart. F2 is in different locations on different versions of the board - however it is usually around the card slot (Metal Slot 1). With the slot facing you and at the top - the fuse is to the right of the card slot. It is a surface mount fuse (but marked on the board F2) it is about 0.5mm wide and 2mm long. To test if this is the problem you will need a soldering iron, heat up the fuse (carefully) and flick it off with the iron, then get a small amount of solder and bridge over where the fuse was. To test, put and hold the battery on to its contacts and try to turn on, if the green LED comes on and then after 3-4 seconds goes off, you have probably fixed it. Reassemble and retest, the DS will not work unless both screens are connected and working. Ideally replace this fuse as it protects the DS from shorting out. It is a 500ma fuse and I have seen them on eBay etc.