What is the name of your state (only U.S. law)? California

I am an independent computer programming contractor in California. I was hired for a project by a person who runs his own company in Michigan to do some work. The contract states I am paid by the hour. He gave me some work to do with few specifications about how to do it. Later he gave me more specifications about how I should do the work and what he needed. But that meant the first few days of work I did are useless. He now believes he should not have to pay for any work (code) he can't use. I believe it's his fault because his initial instruction were vague so I was getting the job done how I wanted, but he later changed things to be more specific.

If he does not pay me, which court do I file a claim with--CA or MI? Would this be something for small claims court if the contested amount is < $1000?