There are a few good sayings when it comes to business and friends:
Lending/borrowing money to friends are a recipe for disaster. Money kills friendships ( I bet there are thousands of variations for this one ).
The hardest thing is to know when to be a boss and when to be a friend, especially if your friend works for you.
My advice is to put the personal aspects aside, and treat this as if someone completely new did this to you, handle it the same way.
Or you could do a last attempt to fix this, but be firm; Tell him that he needs to contact you as this is in his best interest and the possible future actions that may occur due to his poor attempt and neglect to fix or explain the situation, is entirely and completely on his next actions.. This way you leave the ball at his side, of course with a deadline. If nothing happens just start the standard procedures you utilize in these situations.