I asked my dad bout this yesterday. He suggested first sending in the power supply, but then as he thought about it more, he has a new theory. You wouldn't need to wait to hit a pin to get shocked if the source was the bass, cable or power supply. Once you touched the metal housing on the 5-pin cable that would have been enough.
He said that sometimes when you touch something with a small surface area (like the tip of one of the 5-pin connector pins) suddenly, it can really feel like an electrical shock if you hit your finger just right. He's done it before, but not with a 5-pin connector.