Non Payer possible retaliation.

I have a NPB who won an auction on another ID I use , after doing some research I get a bad feeling about this buyer .

I know they can’t leave feedback after I open a case but if they then decide to pay before I close that case can they then leave feedback ?

Or can they claim a refund as item not as described or parcel contained something else  ?

Wish I could just cancel the whole deal & get back the selling fees as the item was expensive .