Curious to see how close I am
Probably starts with a flashback as him as a little kid in a classroom or something. Probably looks at a superhero comic or a science fiction magazine or something and dreams of being a hero.
Flashback to the future he's working hard as an amtuer scientist. When suddenly he's given a project by the United States Government. And this is it. The big break he's been waiting for. His dreams are coming true. Scenes of him working feverishly discovering new concepts.
Then suddenly. It all goes wrong. He realizes his invention isn't what he expected. It's actually dangerous. He tries desperately to explain to the government official but it only makes them more excited to use it. Probably some big military general in the background or something.
He fails and the bomb is used. Probably a sad montage set to some classical music. Then a little text at the end that says "Oppenheimer was undoubtedly a great man who changed the world. Regardless of what comes next"