You can file a claim in small claims court. If he does not show for the hearing, you should be able to get a default judgment against him. The fee for filing in small claims court is minimal, but if you don't have the money, the fee can be waived if you submit an application to file "in pauperis".
You will have to explain to the court that you are not currently able to locate this person, and the court will tell you how to effectuate service.
You should be able to find out where his bank is, by looking at where he cashed the check. Once you get the judgment (default or otherwise), you can arrange to place an attachment on his bank account.
You can certainly call him again, but it is hard to know in advance if it will make a difference. Also, it looks like he is not capable of doing the work correctly, since you said that what he already did looks unprofessional.
If you file, you can always withdraw the complaint if he does finish the work - he will be given time to do so.
Another hint - if you have his phone number, you can try to do a "reverse search" on that number to try to get an address. You can do this by clicking on "white pages" at msn.com.
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