Here is one for the guru community. Here is a list of possible failure (data loss) modes. Please feel free to add to or modify this list. When it is complete I would like the forum to rank them.
1) Physical damage from excessive G force.
2) Logical damage from G force.
3) PCB failure from incorrect voltage applied (power or data cable mishap).
4) PCB failure from IC (EOL)End of Life falure.
5) PCB failure from static discharge (mishandled drive)
6) Platter media failure
7) Spindle drive bearings failure.

Head Preamp EOL failure.
9) HSA mechanical damage from excessive G force.
10) HSA misalignment from excessive G force.
11) Logicl damage from external Software.
12) OHS error.
13) HDA contamination
14) PCB failure from IC/component de-solder/disconnect.
15) Other
Ranking can be either by % or 1-10.