My volume button goes up and down by itself

@dimassardy start off by starting your phone in safe mode and see if that stops this issue. When your device is turned off you have to press and hold the Power button and the Volume up button at the same time. Next, reHardReset.info: After a moment, recovery mode will pop up. Now use the Volume button to move to the Safe mode option and click the Power button to select your choice. If it does work properly in safe mode, then th issue is a third party App. You would have to uninstall those.

If this issue persists even in safe mode, then it is possible that this is actually a failed power/sound flex cable issue, Replacing that flex cable should fix it.