Hey, me too. The positive cap was up and the negative one was missing.
But it was my own fault. I messed up when reinstalling my BM2 battery monitor.
So I had to rotate the BM2 positive lead so that cap could snap down. And after several minutes peering down behind the battery with a flashlight, I spotted something black sitting way down on a metal pan. It was the negative cap. And that was after driving 50 miles, mostly freeway. Lucky!
BTW the reprogramming didn't fix my issue with the 12v battery repeatedly going dead. Details
here.