MacBook Pro can't boot: shows Apple logo then grey screen

There is a MacBook Pro from 2012 with Mountain Lion that won't boot. The Apple logo is showing, the spinning wheel and then it just goes to a solid grey screen.

• I've tried to hold Cmd+R while booting, this does nothing.

• I've tried to hold Shift while booting, this goes to a solid blue screen

• I've tried to hold Cmd+Option+R while booting, this does nothing either.

I'd rather not re-install OS X. Do I need to reset the NVRAM?

Solution 1:

I would recommend following Apple's guide regarding the gray screen at startup.

Have you installed any new firmware/drivers or software that might be the issue? Worst-case scenario is a re-install I'm afraid.

Solution 2:

Try to do a file system check via single user mode.

• Reboot and immediately press Cmd+S
• Wait for the command line and then type /sbin/fsck -fy
• Have a tea. And a cookie.
• Have a look in the output. If the HDD is failing you might see something like I/O Error. If you see something like ***** FILE SYSTEM WAS MODIFIED ***** then you can try to do it once more. If Volume X appears to be OK then you might be lucky.
• Type reboot and let it boot.

More info on apple's website.

Good luck!