OS X Mavericks update 'failed'

Please provide more information such as which Mac Model you have. Your profile says MacBook Pro, but you stated Mac Pro. What is the exact model you have. Are you able to boot the computer or not?

Yes, I see. Get an external drive suitable to backup your internal drive. Then connect it to the computer and boot up. If it is not yet formatted for a Mac, then do this:

Drive Partition and Format

1. Open Disk Utility in your Utilities folder.

2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.

3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed.

4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.

5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.

6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.

Next, Quit Disk Utility and clone your internal drive to the external drive:

Clone Mavericks, Lion/Mountain Lion using Restore Option of Disk Utility

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.

1. Select Disk Utility from the main menu then press the Continue

button.

2. Select the destination volume from the left side list.

3. Click on the Restore tab in the DU main window.

4. Select the destination volume from the left side list and drag it

to the Destination entry field.

5. Select the source volume from the left side list and drag it to

the Source entry field.

6. Double-check you got it right, then click on the Restore button.

Destination means the external backup drive. Source means the internal startup drive.

Last, you need to reformat your internal drive and reinstall OS X:

Install or Reinstall Mavericks or Mountain Lion 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.

OS X Mavericks- Erase and reinstall OS X

OS X Mountain Lion- Erase and reinstall OS X

OS X Lion- Erase and reinstall Mac OS X

Note: You will need an active Internet connection. I suggest using Ethernet if possible

because it is three times faster than wireless.