Lets hope he pays you back. In the meantime you might want to dig down into the borrowers account and gather all evidence linking to them. You might need them in the long run or get another method to contact him.
A word of caution : being generous is a good thing. But this is not like real life. People here are preying on easy victims and giving a non-collateral loan is like giving your money into a ponzi - dont expect anything back; if you do get it back then you got lucky.
Be careful on whom you are lending from now on.
Let's face it: This guy left no shortage of information. His phone number is listed directly on his web-page: https://deadlightbulb.com/
http://archive.is/cPWUl
To be fair, considering the amount of information this guy has publicly available & the low amount of the loan, I wouldn't have expected him to default. Nonetheless, this is good advice. Start caching information through Archive.IS and produce a record.
If OP is infact defaulting, it will make it more difficult for this user to create accounts in the future.