Seller financing could work..........get all SF for two years rehab and raise rents.  

@Jordan RabbI mean of course you can raise value with warranted repairs and good upgrades.

@Nitin Suma  Check your local laws to see if there is a cap on how much you can raise the rent for an occupied unit. 

Is there an opportunity to raise rents at lease end or to improve the units at turnover in return for higher rent? 

How much would the upgrade cost you to raise the rent to 650?

I raised the rent by 3% after one year, and now asked the property manager to raise the rent again by about 3% in six months.

I know nothing about raising capital.

If you actually fix things, are transparent, fair and up front with tenants,  even if needing to raise rents to something that covers expenses, or while digging out the maintenance backlog of a badly undermaintained property,   you are not a slumlord.   

There is 0 unit sold in this condo since city decide to raise property tax by 33% mid 2019, made $6000/year tax became $9000.Family with one child and grandfather living in another 2 bedroom paid off.If rent out: $2400 income. $2900 cost including mortgage tax insurance assessment.

Next is to determine if you can increase the NOI through enhancement in the property, reducing expenses and raising rents which will ultimately increase the value of the property.