If your Mac starts up to a question mark

There is a fair chance your startup volume has failed and needs to be replaced. Please carefully read If your Mac starts up to a question mark - Apple Support. If you still cannot get anywhere please contact your local Apple Authorized Service Provider. You can start that process by clicking Apple Authorized Service Provider Locator (AASP) & Genius Appointment.

Good luck!

There are four steps, followed by If you need help. Describe what does not happen.