It is extremely easy to bork a first-generation My Book World NAS device because it is difficult to know when the device has actually shut itself off.
IMHO, there is one very glaring defect in the design of the original (blue-rings) My Book World NAS device: There is no way to know if the device has well and truly shut itself off. I do not know if this issue affects other versions or not, but I would not be surprised if it does.
This is a problem because the blue "activity lights" are extinguished very early in the power-off sequence, while considerable disk activity remains to be done. Unfortunately, since there is no other way to know if the device has been completely powered down, it is very easy to assume that - since all the lights are off - that shutdown is complete.
This problem is magnified by the fact that we are constantly being reminded to disconnect power from devices that have been turned off to eliminate residual power waste.
If power is removed from the device prior to shutdown being complete, the result can be a badly borked device, or worse. Since there is no indication of activity except the blue rings, it is easy to conclude that the device is not active and then remove power too early.
Add a "pilot light", (power light), connected to the +12 supply going to the hard drives.
What I did was to take a small red LED in series with a resistor of a few K-ohms, and connect it between the hard drive's +12 line and ground.
I drilled a small hole in the bottom center of the front panel, installed the LED and resistor, and hard-wired it to the +12 and ground terminals on the main PCB of the device.
What this does is indicate if power is being applied to the hard drives, (i.e. Are the drives still spinning?), or not. Once the LED goes off, you can be confident that it is safe to remove power without borking the box.
What say ye?
(Note: Since the box is currently on my rack, running, I am not able to provide pictures or a more detailed explanation.)