While you may receive numerous inquiries from individuals casually browsing listings, focus your time and energy on serious prospects.

What other strategies in real estate investing should I divert my energy towards and look at? 

While that sounds like it was an ambiguous situation, furnaces aren't that expensive so it would probably be best to just bite the bullet. 

Along with negotiating the feasibility period and due diligence periods I'd concurrently do 2 things based on your plan:1. talk to the solar companies in the area and understand their site selection process, how they structure their deals, how they operate, etc. 2. talk to the power company and see if they need more renewable energy and if building another solar project in that area makes sense. 

Meaning listing a home for sale will require MORE actions, efforts, energy, intelligence.     

The time and energy you will spend pursuing a remedy is not worth it.  

Real estate had it's reckoning and it's timing, if you didn't get into it and you ever invested in physical assets with size(i'm talking infrastructure, energy, etc.) you'll realize most of these assets are never intrinsic(ITM).

Do you want to put all the money, time, and energy into owning this home/investment?

While you may think three claims could never occur, what happens if a bullet passes through the a home and kills someone and the tenant decides to sue.

Maybe we dodged a bullet or missed an opportunity.