What recourse do I have if they can't fix this issue?

My Honda 2016 HRV makes a weird kind of a rattling sound when accelerating at about 30 Mph. It is new and under warranty. They said they don't know the cause and unless a service bulletin comes out there's nothing they can do. What can I do here?

Lease trying to get rid of vehicle

I currently am leasing a vehicle and the lease is up in February 2018. I do not have good credit so when they refinance the car I know my monthly payment will be high. Because of family situations I know have to move out on my own. I can't afford rent and a car note. My car is leased through Honda. When the lease is up (I'm over my mileage already) can I just return the car and buy a car cash?

I seized my 1999 Miata 1.8 engine. Can I swap in a b20?

So I killed my engine. My question is can I swap in a b20 Honda engine. Those Miata engines are a bit pricey. A b20 is like $800 which is perfect. And if they can be swapped in what all will I need for it to be at Thank you