Button issue not related to the button

Hello everyone,

I need your help. Two days before yesterday, I was so clumsy to drop my New 3ds XL on the ground. I checked if everything was OK and it was. However there was some noise coming from my R button when I used it but as i said there were no other problems. Yesterday, however, when I played SSB4, the ZR button went crazy all of a sudden as if it was hold down the whole time. Also, in the homemenu, it scrolls to the right side. The sound from before disapeared...

I opened the 3ds afterwards and looked the ZR button up but everything was ok. So I removed the ZR and R as well as the other two (ZL and L); I removed them from the motherboard and started my device, but it still scrolls to the right, wherefore the problem can't be related to those buttons.

UPDATE: I was playing Hyrule Warriors yesterday and it stopped scrolling for a few second after I finished playing. Desperately I opend my device again and removed the shoulder buttons from the motherboard and attached them again. Since then, the ZR button works perfectly, whereas the R button does not work at all.

Do you know how I can fix it, WITHOUT sending it to Nintendo (I live in an "isolated" county and I do not have the means to send my device to Nintendo) ?

And sorry for bad English.