What If We Could Reheat the Earth's Core?

Forget a doomsday asteroid or melting permafrost. It’s the freezing of Earth’s core that will end the world in today’s episode. Or would it? Because maybe, just maybe, we could save the world by heating Earth from the inside. What is happening down in the Earth’s core? What would happen if the core froze completely? And would we have a chance of fixing the Earth before it’s too late? What will happen to Earth's magnetic field? What is a superhot core?