Complain to Ebay and Paypal without minimizing what happened. You want and deserve the cost of the machine, the cost of shipping to you and, if he wants the machine back, the cost to ship it back. Call Ebay on the phone (an 800 number). If the seller won't refund your money, Ebay has a 100% return guarantee and they will pay for it themselves. My sister had to go to Ebay and she was given a refund without any questions asked.
Please don't try to repair the machine. It probably will never work properly again. If you try to fix it, then you will not be entitled to a refund. Try again with another machine from a different seller.
Only a fool would ship any piece of machinery without packaging. He was obviously at fault and it is his lesson to learn.
Sorry for the shock and pain you must have felt.