Elon Musk spent the better part of three days on the stand, accusing OpenAI and its executives of deceiving him into donating money to help found what is now one of the world’s biggest AI companies.

The trial between Elon Musk and OpenAI is in its second week, with testimony from former OpenAI CTO Mira Murati.

Elon Musk seems tired and cranky. On Thursday, he took the stand for the third day in a four-week trial stemming from his lawsuit alleging that OpenAI abandoned its mission and should be blocked from taking the company public later this year. If Musk plays his cards right, Sam Altman could be ousted and OpenAI would remain a nonprofit forever.

In the second day of a trial pitting Mr. Musk against OpenAI, he said the company’s chief executive, Sam Altman, had misled him. But OpenAI’s lawyer said evidence showed the opposite.