Check these posts http://community.wd.com/t5/External-Drives-for-PC/Accidentally-connected-19v-supply-to-2TB-WD-Elements-and-now/td-p/834409 and http://community.wd.com/t5/External-Drives-for-PC/Removed-D4-diode-1-0-TB-Caviar-Green-now-powers-up-but-not/m-p/836629#M22597 fzabkar is about the only one who understands these boards. You can alway send him a PM and ask him to lok at your post.
Joe