You can try to turn it in to a battery dealer for credit, but it's likely that they'll tell you "no way" unless you bought the new battery from them.
In the years than I've had the two PC680 batteries in my airplane, I've only had one die. It puffed, likely from overcharging, and I replaced it with a new PC680 that I bought from Amazon. That battery was almost 7 years old. Right now it's sitting in my hangar on its eventual way to it's final resting place. My plan is to anonymously leave it in the used battery cart that sits outside of Automotive at my local Fleet Farm, or just take it to the dump and pay to have it recycled.
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