Good job of tracing back / diagnosing the problem! AND you learned how to use your multi-meter too!

When I bought my first CM30 pump years ago it arrived DOA too! Had to take it back out and install another one! I HATE IT when that happens . . . I feel your frustration . . .

Your thought about some other pumps causing leaks due to higher volume / higher pressure was just a theory that was floated around years ago. No one actually showed that to be a problem. The issue turned out to be sloppy manufacturing and sloppy touch up repairs done by the manufacturer on MANY of the OEM intercoolers.