I know the chemistry somehow reversed. What I would like is an
explanation of what happened in detail. How the chemistry reverses.
Eric

OK:

Parts and pieces, simplified:

Zinc anode current collector.
Manganese Oxide Cathode.
Potassium Hydroxide Electrolyte/Anode

Chemical Reactions = power + heat.
External Heat will increase the completeness of the reaction.
When that heat is removed, there is an opportunity for the reaction to reverse.
When the expansion seal fails (the chemical reactions increase internal volume, and so will cause cheap batteries to leak), oxygen added to the system will react with the other chemicals and start that reverse reaction.

Notice that the reverse reaction is a very tiny fraction of the primary reaction, and needs a considerable and elaborate sequence-of-events to take place:

a) Over Reaction
b) Leak
c) Oxygen

Peter Wieck
Melrose Park, PA