If Disk Utility reports that the volume isn’t repairable, the drive needs replacement. If your Mac fails to boot up into Recovery, there are still a few options.
Alternatively, if this is the very first time an error has occurred on that drive, you might choose to erase the volume and restore from a backup. First, try booting up using Internet Recovery by holding down the Command Option R keys until you see the Apple Logo.
Unfortunately, starting with El Capitan, Apple removed from Disk Utility verify and repair permissions buttons.
Apple claims that all system file permissions are now automatically protected and updated during software updating.
My Mac would turn on, but it would get stuck on the white screen upon startup after a chime.
This white (or gray) screen means that your mac OS or OS X can’t start because of problems with the system’s hardware or software.
If issues continue on your desktop Mac (not Mac Books), its logic board battery might need replacing.
Take your Mac to an Apple Store or Apple Authorized Service Provider to replace the battery on its logic board. Perform a Safe Boot (follow step 1) These Seven steps above should help your Mac deal with the White Screen issue. Turn your Mac off by holding down the power button for a few seconds.
Then you should see a Mac OS X Utilities or Mac OS Utility window.
Select Disk Utility, click your Mac OS or OS X hard drive and select verify/repair disk.
If at all possible, use the Apple branded keyboard and mouse that shipped with your Mac.. Now Turn on your computer by pressing the power key while holding down the Shift key.