1. Semiconductor junctions have a leakage current that is temperature
dependent.
2. Solder joints that are intermittent can be thermally sensitive.
3. A hairline crack in a circuit board can be thermally sensitive.

Others will no doubt add more.


I don't think there is anything more to add.
As you said in a fantastically detailed fashion, it is likely a problem in the
drive electronics which has made one or more critical components thermal
sensitive.

What is important now is determining how the drive sustained such damage to
allow this condition in the first place.

For instance, if it was the result of an overheating problem in the computer
itself, this would be an issue that requires effective ventilation to prevent
it from occuring again. - Reinhart