If a battery with a bad wrapper is installed in a mechanical mod correctly (positive battery pole to 510) if can cause the mod to go into a "auto fire" mode because the exposed area in the wrapper can complete the circuit and act as the switch.
This condition will not cause a battery to "vent" as it is no different than pressing the switch.
However if the same battery with a bad wrapper is installed with the positive battery pole next to the switch it can for sure vent a battery when the switch is pressed if the area with the bad wrapper contacts the mod tube. This condition causes a dead short for the battery when the switch is pressed.
This condition will not cause a battery to "vent" as it is no different than pressing the switch.
However if the same battery with a bad wrapper is installed with the positive battery pole next to the switch it can for sure vent a battery when the switch is pressed if the area with the bad wrapper contacts the mod tube. This condition causes a dead short for the battery when the switch is pressed.