Maybe give them some pointers or tricks to help them be successful.Nothing is guaranteed. 

This is not going to be the most "ideal" scenario that you would prefer, but the alternative would be to go through the lengthy process in housing court which may not guarantee any solution. 

For all loans, amongst other things, I have a recorded Mortgage/Deed of Trust, Promissory Note, and Personal Guarantee in place.Yesterday, out of nowhere, my bank reached out to me and asked me if my business was regulated. 

Understood, hoping you didn't have an appraisal guarantee. 

They advertised them as turnkey and "guaranteed $65k in income every year."

BUYER MAY TAKE “SUBJECT TO” IF THEY ELECT TO DO SO.Government guaranteed rentwhich is exempt from rent control.35% Upside in the RentsNostalgicbuildingin great downtown Oakland area near Lake MerrittExistingCap9%,Market Cap14%ExistingCashonCash Return13.5%MarketCash on Cash Return25%Existing GrossRentMultiplier7.6MarketGross Rent Multiplier5.6HighgrowthcityandareainfluencinggreatappreciationpotentialNodeferredmaintenance-EasyManagementStrongRentUpside.TroublefreeincomeandmanagementOpportunity Zone

Thus the certified finds requirement.The last poster explained the how, they are cutting a cash advance check.Old saying goes, if you can't put a  guarantee on the loan, then the loan is not worth doing.That's the ones thing with real estate, financing has clear cut channels for a reason.

Is this deal isolated or cascades with other investments and guarantees?

I have been in residential construction for some time and know very few reputable companies that would guarantee a 60 day build on anything close to 4500 sq ft.

Just because you replace the old working unit with a new unit doesn't guarantee that you won't have break downs in the middle of hot/cold weather.