I have had the exact same issue. i have been using my 1TB Essentials on MAC with no issues. for quite a while In fact I have 4 WD drives. I received a notification to update my Firmware from WD for the Essential. So I did…stupid me…I followed all the instructions to the letter. When I rebooted my machine the Essentials stays on but I see no activity and it is not recognized as a USB device. I can no longer access it, it does not power down by itself. I am so pissed…**&*&^ I have written to WD, lets see what the reply is… I have lots of content that I do not want to lose. I have read that I could get the drive out of the unit and read the data by attaching is physically to another PC…oh dear WD…I am getting a headache…