Noise from Ext. Hard Drive

I have a 160gb MyBook Essentials model that’s a few years old. Today it was working just fine until I disccnnected it from one computer and wanted to plug it into another (PC to Mac). I could hear a faint whirring noise (NOT clicking) when the device was turned on via the button in the front. The sound occurs regularly (about once every second) and occurs immediately the power is turned on. No warming up/cooling down sound or anything.

Pressing or holding the button again did nothing to the power state of the device. The computer (both the PC and Mac) do not recognize it, although it’s listed under the Device Manager for the PC. I’m guessing the hard drive is getting into some kind of freeze mode where it’s not able turned off unless it’s unplugged.

Any help is appreciated.