the thing is if the failiure is from the harddrive or the controller, if its from the controller, the harddrive is NOT detected or detected incorrectly, if its from the actuall drive, the drive is detected correctly but fails in read/write operations, if its a drive problem, i would put it in the freezer over night and have a usb connector ready to hook it up as soon as i get it out of the freezer, the cold tends to allow damaged drives some operation,
just remember to put it in a sealed bag with some paper towels, you dont want humidity building up,