At 4% interest the payment on this loan would be just over $9200.00 per month, that is without any taxes, insurance, etc. If he is as strapped for cash as he says, this isn't exactly something that REFINANCING will help. But I'm sure you've already thought of that.
I don't know what you're talking about...500,000 loan at 4% is less than $3,000 a month including everything. Tell me how you came up with $9200...