Check your board for damage to diodes D4 and D3, and zero-ohm resistors R64 and R67. If you have overvolted your drive, then I expect that D4 will be shorted. If so, then the fix is to simply cut it out with flush cutters. However, be absolutely certain your power supply is good, as you will have removed the overvoltage protection from the +12V rail.
Is the PCB is the same on each caviar green hard drives ?
The intention is not to change the PCB (it seems that WD has made things to make it really impossible) but to check if this quoted solution can be applied on this hard disk that won't spin up after a power break caused by short-cut in the power supply that powered this external hard disk (thru a simple sata/usb adaptator and external 12V power supply that died since).