Z3 Roadster (E36/7) Water where it ain't supposed to be

A few days ago we had a very heavy rain here in Western NC. Afterwards, I reached into my trunk to retrieve an umbrella... and was greeted by a minor flood, including a couple of inches of water in the battery compartment. Turns out my brand new top was installed with a tiny flaw -- a kink in the butyl rubber tape sealing the top from the rear of the car, allowing a substantial stream of water into a normally protected area. The car is back at the auto upholstery installer; the top will soon be detached and correctly re-installed. Apparently no one did enough of a test for proper sealing the first time before handing the car off to me. Dry car, please!