Or the Atomic Energy Agency decides that Thorium based nuclear reactors would make proliferation free nuclear energy too cheap to meter, for real, and that would cut into the profits of the energy sector.
Or that Tesla had a means to tap into the Terawatt of energy stored in the ionosphere from the charge of solar winds, and JP Morgan was interested in selling copper wire instead.
There are many, MANY different ways things could be different, some of them actually plausible.
Random idea that just popped to mind:
The reinvention of Microsoft (or "Seemingly-Outdated-Fictional-Megacompany-X") as an open-source, progressive tech pioneer. I don't know the details of the history here, and I'd make up a different name for the company to give me more leeway even if I wanted to keep details as accurate as I reasonably could.
The story of a company (Tinyhard Corporation) whose founders viewed open-source as a threat to their company's very existence. A scourge upon the world! Or rather, maybe a story from the perspective of a long-time employee (or group of employees) who started off fully believing their company's skepticism toward open source software.
Through their eyes we witness things like the Halloween (or "Christmas", for Tinyhard) documents and other internal communication about their employer's anti-open-source stance. Maybe the main character is intricately involved in putting into motion some of the company's tactics to squelch the rise of open-source software?
But then something happens (an "inciting incident"), during the course of our main character's efforts against open source on behalf of the company. The employee or group start becoming converted toward open source acceptance. These characters can be entirely fictional, showing us true (or inspired-by-true) events of the company through their eyes. Maybe the employee meets a rebel who they first see as an open-source-loving, good-for-nothin', irresponsible hacker who doesn't understand how bad open-source is and a love interest develops that also surfaces questions about everything they believed about their fight against open-source.
Maybe as they are converted, they slowly start advocating and eventually fighting for open source internally, sowing dissent (resulting of course in conflict and a threat to their position).
The culmination of this character's efforts results in Tinyhard's first ever open-source release: Tinyhard Intaller XML (TiX).
That can be the end of the story: the first step toward a brand new world. An ending of our character taking one small step for them, one giant leap for the future of Tinyhard.