Peter wrote:

I have a Western Digital 160 GB External USB 2.0 HDD
(Model # WD1600B008-RNN). It was working well and good
and suddenly it stopped working when I wasnt around. My
brother was using it and he says he may have changed the
polarity for the DC input. I had a DC adapter which can accomodate
multiple heads. I changed it to right polarity and switched it on.

When I switch it on, both the green and red lights are always lit,
PC identifies that there is a USB device connected, but it cannot
"see" the Ext HDD. Windows Drive Information did not list this drive.

I tried with WD Data Lifeguard Diagnostic for Windows program
that lets the PC to identify the drives but the drive did not show
up. I tested the input power cable and it is working.

I suspect there is a board failure as the DC polarity was mixed up.
Since I dont work much on storage hardware, I suspect that there
should be a control mechanism/fise which may prevent the
board/hard drive from being fried.

So what would be the next logical step for trouble shooting ??

Is it still under warranty ?

It is rather impossible to change DC polarity for those devices by mistake.

Not with the DC adapters with multiple heads, very easy with most of those.

How valuable was data on that drive?