Invest the money into the stock market, continue getting greater returns, sell covered calls to get more returns at still low risk, but have the liquidity that you could pay off a property at will should the need arrive.

A market and neighborhood that is more established and has higher growth should allow you to exit or refinance faster while extracting a larger percentage of your initial investment.

Meaning take the cash out you need have one loan, rate, payment and most importantly cash in hand -liquid reserves. 

So more capital required, but from an execution perspective it may actually be easier because the difference between the purchase price and after rehab value is typically also much larger, providing more margin for error and also making the potential reward much higher.

I've done fairly well on startengine.com had three larger returns in three years out of 9 investments so am ahead of my expectations. but remember all could fail so do your due diligence and do not put in more than you could afford to lose.

Second, its not liquid, you need to sell or refi to access that value and use it.

I have 3,200 in liquidity and I estimate I should have north of 5,000 before the school year is over(we have been flipping furniture on Facebook marketplace and have made nearly 1,000 in the past 4 weeks). 

My initial thought was to liquidate the brokerage account for the downpayment.

I like mitigating loss of revenue if one tenant moved out and I planned to go into larger multifamily properties in my 5 year goals.

Like @Lorenzo Wright said, this property could go downhill quickly, and I think you need to mitigate the risk by negotiating repair for the larger items by the sellers.