Interesting scenario - generally these are situations where an appraiser would use the cost approach when estimating the value of the home or go wider in the parameters for finding comps.

Raising rents to market, doing those fixes in theory raises the value when using the income approach.

The down side to this approach would be that the portfolio then becomes all or nothing.

I do not know how the counter was damaged but trying to go down the path of expected life span is likely not your best approach.  

How should I approach the situation to get the owner interested to sell???

We do not have a mobile app, but our Website is mobile-friendly on a smartphone (most online rent payment services use this approach).

We would either move into another SFH or follow @Tucker Cummings house hacking approach.

If you can’t develop approaches for the above, walk away from the deal.  

@Ryan Howard welcome...doing some more research on your desired path should shed some light on the environment you're working in...I would caution noting that you do not have capital, but want to wholesale to raise capital...you're essentially admitting you are trying to broker real estate without a license...you will hear lots of opinions on this, but the bottom line is if you have no intent to close on a contract you enter into, you're engaging in unlicensed activity and subject to $1,000/day fines.I'm not saying don't wholesale...I am saying do your homework so you don't end up in a tight situation.Taking time to explore every option in RE investing is not a good approach...I can save you years of heartache and you'll be wealthy much faster by sticking to fundamentals...long-term buy and hold real estate is the only path you need to go down. 

I think a better approach is working together.