That link gets you to this: If your Mac doesn't start up all the way - Apple Support
And the folder-with-question-mark icon gets you this: If your Mac starts up to a question mark - Apple Support
That link gets you to this: If your Mac doesn't start up all the way - Apple Support
And the folder-with-question-mark icon gets you this: If your Mac starts up to a question mark - Apple Support
That link gets you to this: If your Mac doesn't start up all the way - Apple Support
And the folder-with-question-mark icon gets you this: If your Mac starts up to a question mark - Apple Support
If nothing else works and to simply get out of this situation, press and hold the power button until the Mac shuts down.
Doing so is not likely to harm your computer, they are built to live through expected power outages while operating.
My iMac froze on support.Apple.com/Mac/startup , how can I exit from it?