Hardware R button making me SUPER MAD!!!

[TiredLink]

Once upon a bad time, I bought a USED 3DS (don't ask why) and the R button didn't respond!

And now I'm still here!
Sometimes the R button works!
Sometimes not!
Sometimes it goes active "forever" (not physically because the button is not being held)

Like, I've tried EVERYTHING!
Blowing, cleaning it, pressing it hard AND EVEN sucking all the dust like Kirby!!

Nothing!

Like I said above, the R button is LAZY, it works whenever it WANTS!!!!

(Never buy used stuff kids or it will be WAAAAY too late)

your ds reminds me of my xbox controller anyways, dismantle them and add some new ones and if that doesn't work it's prob the sensors.