New to Amazon. Sellers returning perfectly good items. Can I get refunds?

I have sold a few items that sellers have returned with excuses of being defective or that they needed a power supply with more power. The long story short is that the items were working perfectly all the time.

Does Amazon provide some sort of refunds in situation like these, like the selling fees and return shipping?

I have been checking tutorials and such and i could not find anything other that we can return either 50 or 100% selling price. I see no option like for restocking fees.

Obviously, those fees are piling on and killing me.

What are my options here? Am i missing something? Tia