Mac won’t start
Our Mac won't startup but only dispays the apple logo and progress bar. I tried shutting down, and restarted continuously holding the start button, but no menu ever appears. What to do?
iMac 21.5″, macOS 10.13
Your Mac has likely had a hardware failure and will need to be taken in for service. Assuming you have been backing up daily your data is safe. Before making an appointment to take it in ( Apple Authorized Service Provider Locator (AASP) & Genius Appointment ) please try the steps in If your Mac doesn't start up all the way - Apple Support
Best of luck!