This was mainly a QC problem. Batteries were produced with an unusual rate of defects that resulted in internal short circuits. Cramming the battery in to the s

This was mainly a QC problem. Batteries were produced with an unusual rate of defects that resulted in internal short circuits. Cramming the battery in to the smallest space possible may have exacerbated those defects, but batteries for consumer applications should not be so fragile that moderate pressure on their shells causes them to explode.