What is the next step in tf he suns life cycle after it has used up its hydrogen fuel

Once it has used up its hydrogen fuel, it will then become a supernova. The reason is because eventually the core becomes heavier and heavier because more mass flows into it after its fuel is used up, and then the strength of the gravitational force causes it to collapse on itself and create a giant explosion. From there, it then can turn into a black hole or a neutron star.