I have bought a battery from a warehouse that was backwards, - I never installed it as I have a habit to check the battery in its isolated state before I install it.

The only way I know that can happen is if the battery has been activated backwards because to charge it backwards your battery should be having close to only 2V when applying the charger. Most chargers will shut down when connected backwards on a depleted battery (11V)

In any case if you connected it to the car, a lot of fuses would have popped.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)