This dreaded flashing question mark inside a folder means that the startup disk is no longer able to find a Mac operating system to boot from. There are a few things you can try to do to fix this yourself.

Reboot MacBook pro and then hold the Command (⌘) and R keys on your keyboard to startup from the macOS Recovery. I did this and was able to go through disk diagnostics telling me that there were some disk errors. I proceeded to fix what I could but found that on subsequent reboots to macOS Recovery showed different partition errors. Sometimes the disk utility completed successfully but other times it would stop repairing even if left overnight.





If you did have a failing disk drive, the marked errors would be consistent and multiple passes will bypass these marked errors. I had erratic results however which led me to believe it may or may not be a bad disk. The next investigation should be to look at the disk drive connections to the SATA controller.

Open the MacBook pro and take a l…