If the internal speakers on your Mac aren't working
If you don't hear sound from the built-in internal speakers on your Mac, make sure macOS is up to date and check your settings.
Check your sound settings
First, disconnect any cables from the USB, Thunderbolt, or 3.5mm audio ports on your Mac.
- From the Apple menu , choose System Preferences.
- Click Sound.
- Click the Output tab, then select the built-in speakers. If you don’t see built-in speakers as an option in the Output window, contact Apple Support.
- If the Output volume slider is set low, move the slider to the right and test again.
- If the Mute checkbox is selected, deselect it and test again.
- If you still don’t hear any sound, contact Apple Support.
How are you shutting down the computer ? By what means / measure are you determining the computer is not totally turned off ?
When choosing to shutdown via Apple Icon >> Shutdown are you Unclenching the Dialogue box to Not Open Windows when logging in ? If yes, then suggest go to System Preferences >> Users & Groups >> Choose your Account >> Left Side and look for Tab Called Login Items. Inside there are Applications set to startup when the computer starts from a Cold Boot. Remove all items you do not what to start.