I am working with Energizer AA alkalines
I just reflashed the firmware with the original LEGO software and figured out an infinite loop with their GUI tool (I'm a Java dev, so I barely looked at this to start with). Same problem
It's weird that it cuts out at exactly the same time, every time. I'd have thought a thermally triggered switch would have some sort of variation in timing...
I'll contact Lego tech support and let you know.
Thank you so much for the help and effort!