What kind of professional would be best suited to provide guidance on a complicated real estate/financial problem?

A friend of mine (no, this isn’t me), has a complicated problem. He bought a house with the intent to renovate and flip it. His best friend did the renovations, at a huge cost, but now the house won’t sell. He’s bleeding money to the banks every month (interest only), and it is killing him. I think he needs professional help in the form of an accountant or lawyer, but I’m not sure who would be better or where to go about identifying such a person. Any suggestions would be greatly appreciated.