Complex sentence: Carlos is awake and Forward tells them that he'd found the quantum black hole just before the Institute of Knowledge cut off his funding while he was looking for the Tunguska meteorite, which he believed had been a quantum black hole.
Split into simpler sentences: Carlos is awake and Forward tells them that he'd found the quantum black hole just before the Institute of Knowledge cut off his funding. He had been looking for the Tunguska meteorite, which he believed to be a quantum black hole.