How did Franklin Richards die in the marvel universe?

Franklin Richards, a powerful mutant and son of Reed Richards (Mr. Fantastic) and Sue Storm (Invisible Woman), has had various storylines in the Marvel Universe. In the "Heroes Reborn" storyline, he is depicted as having ultimately sacrificed himself to save the universe, merging with the cosmic being known as the Living Tribunal. However, it is important to note that due to the nature of comic book storytelling, characters often return or are reimagined, and Franklin has had different arcs, including his resurrection in subsequent storylines.