The company stated, "The closings were brought about by the rising cost of doing business in California."

Yearly net cashflow after absolutely all costs and a margin of safety should be between $15,000 - $20,000.Lessons learned?

Is there a way to accurately evaluate the repair cost of this kind of issue? 

I have considered creating my own Property Management LLC to do the work above and hiring my dad as an employee, however, I was told this would provide no benefit in terms of liability and it would just add costs and more taxes.I would appreciate your feedback.

Did it one time cost me.  

You need to find a deal that works under beginner terms.Hard Money/Private Money works when the deal is good and when margins are thin it can be costly that's why sticking to max project cost being less than 72.5% ARV is key.  

A PM can cost you 10-15% per year but they can also keep you at market rate and protect you from losses.

Sewer problems can be quite costly. 

Off market is often a myth unless you are the one perhaps generating the leads, but then again that cost money and time and effort. 

Even missing one component can cost you tens of thousands of dollars.