My friends MacBook Pro from 2012, with Yosemite installed on it, has experienced a melt down. Basically whenever it starts up, you get to type in the password (FileVault is enabled), and it starts going through the startup process. However, about 15 seconds in, the bar has barely started moving, the MacBook just shuts down. I tried booting up in safe mode, but the same thing happens. I then connected it to my Mac Pro via Thunderbolt, booted the MacBook up in Target Disk mode, and was able to get the user directory offloaded. As you can see on the attached picture of the boot process, the last message is "Invalid node structure (4, 18441)", "The volume Macintosh HD could not be verified completely.", "Boot task failed: fsck-safe", "Shutting down in 3 seconds." Do I have any way to recover from this, or is it a complete reinstall?