I know it's a common question but I've found no answers online so far. My professor has made a point out of saying that fusion reactions after iron and nickel do release energy but just not enough to keep the star from imploding. This didn't make sense to me. How would fission release energy if that were the case? Every where I've looked online says that it does in fact take energy for fusion after iron and nickel. I even did a little numerical calculation for for nickel-62 fusing with an alpha particle to make zinc-66 and found that it's preferable for it to stay as its constituents.