Macbook pro stuck on "folder icon with ?" on startup.

• If your Mac starts up to a question mark - Apple Support

https://support.apple.com/en-us/HT204323

"A folder with a flashing question mark means that your startup disk is

no longer available or doesn't contain a working Mac operating system."

You may try these options shown, including macOS Recovery

and Disk Utility for repair of Mac's system; or reinstall, etc.

..The rest of the article covers other important details

& include blue text links to Apple Support database..

The first two after example/images are conditional.

"IF the Question Mark appears Only Momentarily"

[Then, these go to other useful actions for you to follow.]

1. Turn on your Mac and immediately press and hold Command (⌘) and R to start up from macOS Recovery.
2. While in macOS Recovery, use Disk Utility to repair your startup disk.
3. If Disk Utility found no errors or repaired all errors, reinstall macOS.

..Good luck & safe travels..!

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