I Think if a persons local and selling a High Dollar drone....the buyer needs to meet at a nice flying field so the seller can fully demonstrate to the buyer with cash in hand That the drone flys " just like new "......the parts inside a drone are sure not cheep...and some knowledge is required to un solder wires and re solder them back in the right spots many times bargains are not bargains in the long runn....The best of luck in seeking what the " ESC " problems are...I above posted a link here on PP of many others that also has had a ESC issue.