It appears that your drive has a shorted TVS (transient voltage suppression) diode. It has sacrificed itself by going short circuit in order to protect the rest of the electronics. There will be two TVS diodes, one for the +5V rail, and a second, usually larger one, for the +12V rail. If there is no other damage, the solution is to remove the shorted diode by desoldering it, or by snipping its pins close to its body with flush cutters. Just be sure your PSU is OK, as you will no longer have any overvoltage protection on the affected rail.
If, for continued protection, you wish to replace the diode, then a 5V TVS diode can be substituted with an SMAJ5.0A, and a 12V diode with an SMBJ12A.
They can be ordered from Farnell, Mouser, Digikey.
As for board replacement, generally speaking, a straight board swap will not work for modern drives. This is because each drive has unique calibration data which are stored in a serial EEPROM (flash) chip. When swapping boards, this chip must also be transplanted from patient to donor.
This following URLs should help you identify the components:
http://hddscan.com/doc/HDD_from_inside.htmlhttp://www.users.on.net/~fzabkar/HDD/HDD_ICs.txthttp://www.users.on.net/~fzabkar/HDD/TVS_diodes.txt