side volume button will only turn down

There's a dome underneath the volume key on the droids that will sometimes get metal shavings underneath it.

Follow the guide for taking the droid apart and check the dome under the volume up key after you get the back housing off, being very careful to remove the dome and sticker as one piece, since you'll have to put it back on. You want to make sure the tiny black dot between the orange sticker and the dome stays in the center of the dome.

Cleaning the silver/gold area on the housing that the dome set upon with a toothbrush and alcohol should help and also check the dome itself for any debris and scrape any off with fingernail or very gently with a small flathead screwdriver. Make sure to let the alcohol evaporate completely before putting the sticker with the dome back on.