Dead 500GB WD5000E032 'My Book'

I have been testing a faulty 500 GB WD5000E032 ‘My Book’ for a friend (I am an Electronics Engineer). The My Book serial number is

It won’t power up when pressing the button or when it is connected to a USB port but in a dark room it is possible to see the blue LED flash faintly every second or two. If connected to a USB port, Windows XP repeatedly detects it then says that a USB device has malfunctioned.

If I disconnect the internal WD5000AAKS 500 GB hard disk inside the My Book and connect another SATA hard disk in its place (WD400BD 40 GB) then the My Book powers up and provides the correct +5 and +12 V supplies to the hard disk. The My Book is recognized as a USB device and the contents of the 40GB hard disk drive can be accessed via USB.

I have tested the My Book power adapter unit and the electronics in the My Book box and both are able to supply adequate current on +5V and +12V. The fault is in the WD5000AAKS 500 GB hard disk itself. It is trying to take far too much current from the 12 volt supply and this causes the power supply circuit in the My Book to shut down as soon as it tries to start up. If I try to power the hard disk from a separate +5V and +12V power supply (with current limit), it should only take 0.55 amps from +12V but it is trying to take more than the 2.5 amp limit of my power supply while pulling the 12V supply voltage down below 2 volts. Powering it from a PC power supply with high current capability would almost certainly cause something to burn out in the 500 GB hard disk.

It seems that the motor drive circuit in the hard disk drive has failed and is putting a near short-circuit on the +12V supply. The WD5000AAKS 500 GB hard disk was manufactured May 2007 and failed in April 2010. I wonder whether this was caused by a failure in the WD5000AAKS 500 GB hard disk drive itself or whether it was killed by over-voltage on the +12 V supply from the My Book electronics. Has anyone else had a failure like this?

The disk drive contains data that is not backed up elsewhere so the owner is looking at a professional data recovery service costing hundreds of $$$.