Call utility company? 

Real estate investing is a team sport.

I've looked at his utility/mortgage bills and estimate that getting $1800/mo would cover all my brother's current expenses, plus setting aside 10% of his expenses for vacancy, 5% of his expenses for capital expenses, and 10% of his expenses for repairs & maintenance.

The realtor was able to find out that all the units are individually metered for utilities and all utilities are paid by the tenants. 

If not , make sure you have individual meters and the tenants pay all utilities including lawn care.

I notice your utilities are blank in your analysis. 

@Susan FerrisYou can utilize the BRRRR method.  

I'd see if she leaves the utilities on or turns them off and make a decision based on that.

For costs, there is more than your mortgage, you have property taxes, insurance, utilities not to mention repairs.

No HOA or CDDsTotal monthly = 2,335If Short Term which I have confirmed as legal in this neighborhood then add utilities say an additional 400 = 2,7351) Now Step one would be to house hack for the first year or two.