Legal Question in Civil Rights Law in California

The general process is to file a motion to set aside the judgment. That won't result in a dismissal, but it will allow you to defend against the claim. The precise way you go about that motion depends mostly on how the plaintiff's proof of service shows you were served with the papers.

You will need to get a copy of that proof of service from the court file. There are services that will help you do this. Alternatively, you can contact the other side, say you do not believe you were properly served, and ask for a copy of the proof of service. The other side does not have an obligation to provide this to you, however.

The motion is not simply a set of forms you can fill out. You need to actually draft the papers, in proper form. While you may not to fly back to California, you almost certainly will need to hire an attorney licensed in California to help you. The attorney will prepare and file the papers, and then appear at the hearing. (I assume this is not in small claims court, where an attorney cannot appear for you).