Try this . Music has stopped on my device .

Go to Settings  (press central button , navigate left til reaching Settings.

Click on Central button

Click User Profiles.

I  clicked Outdoor as I am partially hearing and need extra audio strength.

Click Options

Click Customise.    Here you can adjust the tones and volume. BUT  to stop the music scroll down to Power On     choose silent .  Then down to Power Off.  Then cover open and cover close  and press SILENT for both.

Note I saved each in turn.  Which meant going back in and out of the settings.

Also note I changed the settings for the same Silent mode for GENERAL as well as OUTDOOR.  To be sure of silence. This maybe something U experiment with .

Hope this helps.  USER PROFILES are very useful to gain the most from any phone. Ringing tones , volume etc