What do I do with his security deposit?

And I already took the listing down and cancelled a couple people I had booked to show it for today.Would you keep the security deposit only?

If we eat healthy every day, the weight will come off. 

First off, the odds of you ever being sued for anything more than a security deposit dispute are extremely slim.

@Josh Caldwell Josh, do you think hard money strategy can be employed for securing a multi unit (4 units residential) if secured with a HM lender who will refinance the original loan after a specified period of time?

What are key factors that weight into who you chose, and why are those important?

If it is nearing the end of its lifespan, just replace it.Tarp is going to look bad and will create other holes in the roof when you secure it. 

Sometimes a high upfront acquisition fee, can be because the split is weighted heavily in the investor favor.

Might even be able to charge a bit extra in rent for video security:)

If you do those 3 things you will be able to help them secure an investment property, make necessary repairs(at a decent price), and get the place rented and cash flowing.