My MacBookPro (mid 2012) will not complete the boot process. Yosemite's progress widget gets about 1/3 to 1/2 way across when the logo disappears and the screen goes all white for 10-15 secs or so, then the machine shuts down and restarts.
I upgraded to Yosemite from Mountain Lion a couple months ago, skipping Maverick completely, and I've done any associated updates that Apple told me about. I don't recall which version of Yosemite I have, but I'm sure it is the "latest and greatest".
I've tried re-starting in Safe Mode / Safe Boot and that does the same thing as described above except without the endless restarts. Instead of restarting at some point, SafeBoot proceeds to the white screen and then it hangs until I restart it manually. (I've waited as long os 20-30 minutes with no response).
When I tried the option-command-p-r key combo I never get any chimes or other noises besides the original 1 time boot sound that you would expect to get when starting up a macbook pro.
I was using the mac quite normally (meaning I was doing work I normally do on it and there was no indication of anything wrong) immediately prior to this happening.
The machine is BootCamp(ed) with Windows 8.1 which I use from a VMWare virtual machine instead of natively so that I can have both OSes running at the same time. I also think this is unrelated to my problem. I have been using this setup for more than 2 years.
My upgrade to Yosemite was uneventful and I thought it went well and was very smooth. I don't want to lead attention away from Yosemite, but at this point my problem does not seem related to the upgrade.
Any help is appreciated.
Install or Reinstall OS X from Scratch
Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Erase the hard drive:
1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your startup volume (usually Macintosh HD) from the
left side list. Click on the Erase tab in the DU main window.
3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on
the Security button and set the Zero Data option to one-pass. Click on
the Erase button and wait until the process has completed.
4. Quit DU and return to the main menu.
Reinstall OS X: Select Reinstall OS X and click on the Install button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible
because it is three times faster than wireless.