How to correct this defect

I had that happen on a Droid Turbo 2 repair. Turned out, the owner had splattered soda on the phone and the keys were sticking down. The phone was looping because the power and volume down keys were stuck down. I used a soft art paintbrush and alcohol to clean the stick out. Don't wet the board and keys to much. Just a little at a time should do the job. If that doesn't work, you might have to do a tear down and remove the buttons from the device. Do be careful and always use a strainer in the sink so you don't have to order new keys.