Uhmm.... I think the only way you can temporally fix it would be blowing on it. But if some vapor gets there it'll kill your ds. The best thing you can do is to buy a can with compressed air and take it apart or get somebody to take it apart and apply it on the button switch. But still there's a chance it will stop working again (Some months after). Just remember to keep your ds away from dust.
The has been a reoccurring problem on Nintendo handhelds since the GBA. You have two possible solutions: 1) Disassemble your DSi using a tri-wing screwdriver and blow compressed air into the button casing. The compressed air has a good chance of clearing any dust. 2) Hit the DS (right on the shoulder button) hard against a corner or hard surface. The shock has a good chance of moving or clearing any dust. 3) Send it to Nintendo. Free repair/replacement if it's under warrantee. $30-50 otherwise. A friend and I have exclusively used method (2) with stellar results. He karate chopped his DS lite to fix it once. I personally prefer wall corners. To prevent dust from collecting in a shoulder button use a case or bag for your DS rather than just your pocket. This topic has been done before and will be done again.
i had the same problem with my L button, i used compressed air and sprayed it under it the best i could and it's seems to be working better, but then again, it's only been a day since i did it
Yeah...This is a pain in the ass. I had the same freakin problem on my DS Lite. The L button sometimes work and sometimes doesn't. I had to press the L button harder onto the corner just to get it working...
Having the button somewhat working but not entirely is classic dirt/dust in the thing. Bang the offending shoulder button really hard on a corner, no joke.
How could the warranty be out? The DSi came out in America (considering fact that you're american) IN April the 5th. It's impossible for it to be out of warranty unless it's a Japanese DSi.
Just wanna let you know the DSi doesn't need the tri-wing screwdriver at all to be taken appart (I fixed mine's R button by adding a piece of tape between the pad and the button for better contact...)
