Put BRF Jars Near Heater, One Stalled And Smells Like Bread

So I'm living in a new house with little insulation, and I have BRF jars of Cambodian cubes in the kitchen I want to keep warm. I set up a space heater a distance I thought was far away enough, but after leaving it on for 8 hours overnight the 2 jars closest to the heater were warm/hot-ish to the touch.

Since that night, one jar completely stalled. It was like 80% done. I flipped it over to help the bottom colonize, but nothing.

I opened it up to fill it with water and see if I can fruit anything off it, but when I took it out it felt spongey, not firm like normal, and it literally smelled like bread.

I assume the heat stalled it and allowed bacteria to thrive? At least I know to never do that again and just leave them alone. What is the lowest temperature they can stand while colonizing a jar, though?