That hasn't been my experience with FedEx Ground. I sold an amplifier to someone a year ago and it arrived damaged. It was double boxed (by me) and had the original styrofoam protective inserts. The box quite clearly suffered a long fall, and the chassis was bent out of shape.
I believe it's the seller's responsibility to get goods to the buyer in one piece, so I immediately refunded the seller's money, and as the originator of the shipment, I filed a claim with FedEx. It took them about 2-3 weeks to schedule an appointment, but they went out to visit the buyer. I had to follow up a couple of times, had to submit a quote for repair (it exceeded the selling price) and it took another 2-3 weeks to get the refund.
I did get the refund, and it wasn't too much hassle. They let me keep the amplifier, so I asked the buyer to send the amplifier back to me, and then I offered the amplifier for sale to the manufacturer, assuming he might have a use for it as repaired B-stock. It just turns out people are more likely to buy a repaired amplifier from the manufacturer than from a private person.
I actually came out ahead of the original sale.
With respect to the damaged crock pot, regardless of whether the FedEx approves or rejects the claim, isn't it the seller's responsibility to get it to the buyer safe and sound? If so, ask the seller to accept the return, or if that doesn't work, then file a claim with EBay, the credit card company, PayPal, etc.