Chances are, if you took it back to Lowes and said you bought it there and it was defective, chances are they will take it back no questions asked (that is their policy) and since you wouldn't have a receipt, they'd give you amerch credit. When I worked at Lowes, we took back everything, even paint that was tinted to the exact color they needed, but they didn't want anymore.
Although morally, I would consider it stealing. However, chances are they'd send it back to the manufacturer or get a manufacturer credit and destroy it on site. In that case, I don't know where I stand morally, I'm on the fence.
