What should my son do if he is bullied in Xinling Gui Long Metal?

I was fired. A few months ago, I didn't think I had done anything wrong, but I was fired. Maybe the manager of the network center was such an asshole that he fired me. He also said that he wouldn't let me ask for compensation, that he wouldn't scribble on the file and couldn't find another job. His personality is too bad. The administrator is good, but there is really nothing I can do with this sb manager. He asked the company to be open-minded and reasonable. How can such employees ask for it, and how can they be leaders?