That's a difficult problem.
Anything else behaving strange?
Try a few things first:
Restart your phone and see what happens.
Restart your phone in safe mode and see what happens.
Goto the Support app and check if there are software problems.
If you have an SD card inserted, take it out and see what happens.
If nothing helps then push Vol-up and Power button for a long time, neglect all buzzing and keep pushing for a minute.
See what happens after a restart.
If that doesn't help I'm at a loss, because there is no indication.
Well, one more thing: an app you installed recently is causing problems.
Tell us more.
