Ebay ?
If sold in the condition category "Used" they MUST work as intended by DJI.
It does not matter if the seller puts "no returns" in the advert's blurb, if the drone does not work and is in the Used category you have grounds for a Not as Described return and ebay's T&C supercede anything written in the advert.If they don't then you are entitled to return the drone, at the seller's prepaid-postage expense for a full refund which includes the original carriage charge to you.
You would have to follow eBays T&C & timescales for the return, the return MUST be via trackable means and all correspondance with the seller MUST be via ebay messages .... ebay staff may want to read them.
That is the way ebay works in the UK and I imagine ebay USA is much the same.