Can't close if shed isn't taken down. Seller won't allow it.

I am in the process of purchasing a house. After the appraisal, I was told the large, worn shed in the backyard needs to be torn down. It would cost around 6k for it to be taken down. The seller isn't willing to pay for any portion of it, nor are they even willing to allow for me to pay for it to take it to be taken down. Their excuse is that the heavy machinery will damage their yard and potentially their septic. I have tried to look at other lenders, but they have told me the same thing: the shed is in very bad shape and needs to be torn down.

Closing date is a week a way. It is very likely I will not be able to close.

I paid 4k in due diligence. Is there any way I can get any of that back in this situation?

Any advice appreciated.