I have a MacBook Pro with Retina display, when starting up, I see the Apple logo, the bar underneath fills about 1/4 of the way, and then the screen goes black, the mouse cursor is still visible.

Question

Boots to black in OS X mode (I believe 10.10.2? tough to check right now).  I can boot into Windows 8 using Boot Camp without incident.  I have booted to Disk Utility and run Disk and Permissions Repair.  I have booted into Diagnostics, and no issues were found (ADP000 was the Reference Code given).  I reset the PRAM, which gave a louder chime than I had been getting when failing to start up OS X, but otherwise no change.  Feeling that my options were exhausted, I attempted to restore from Time Capsule, and it won't connect to Time Capsule, despite Time Capsule being the active router whose network I am connected to.  Please advise. 
(This is my girlfriend's computer, she tells me that she selected an option to perform an automatic update later, that night.)

Answer 1

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.
This should install the version of OS X that you had installed.
Be sure you only work on the OS X volume, not your Windows volume. I cannot tell you if you will still be able to boot the Windows volume after the above. You will need to find a fix for that.