What happends first when a star begins to run out of fuel

If a really huge star dies, it has so much mass that after the helium is used up, it still has enough carbon to fuse it into heavy elements like iron. When the core turns to iron, it no longer burns.The star's gravity causes it to collapse, and then it explodes into a supernova.

Hey the answer is The core finally cools into a white dwarf, then a black dwarf. This is what happens when a normal-sized star dies. If a really huge star dies, it has so much mass that after the helium is used up, it still  has enough carbon to fuse it into heavy elements like iron. When the  core turns to iron, it no longer burns.The star’s gravity causes it to collapse, and then it explodes into a  supernova. What’s left of the core can form a neutron star or a black  hole.