This is the scenario:I buy a fixer with some hard-money.

If you're willing and able, I do recommend the "house hacking" strategy which is just a fancy name for buying a rental property and living in one of the units, because you'll get very favorable financing - an owner-occupied fixed-rate 30-year mortgage.I'd also say, analyze that property as if you won't live there and it's a pure rental, and make sure the property is still cash flow positive if there's a tenant in your unit because then you'll know if it's actually a good investment.And when you analyze it, include payment of a property manager in your #s because if you don't, and doing so would make it go cash flow negative, then you've just bought yourself a job because you literally can't step away from managing it without losing money.

Should i sell my business to get this money?

I bought this property with a private interest free loan from a friend. the person i bought it from need cash fast so i offered them a low cash offer and they accepted.I had enough money saved up to rehab the house with my savings.

The refund part is just to get you get committed to another deal that makes them even more  money than that refund.

What if you need to inject more money? 

I think $10k/mo is good money, other people live in expensive areas or have higher taxes and need $20k.

DSCR loans are not that low and regular hard money loans will be in the double digits.

That's where good people live, and good people make good tenants.But before you put money down on a house, I would find a quality property manager.

You can attend all the REIAs and read all the books and sign up for all the conferences, and spend all the money, and you are will never really know you can do it until you do.Over 20 years in real estate in various forms and roles, action will beat out intelligence or education or even network 100% of the time.