My Ryobi Tool Isn't Working Due To Manufacturing Defects

I bought a new battery about a year ago, an inexpensive one indeed, it stopped working just a week ago. Even though the charger shows a full charge, it simply won't work with any of our Ryobi devices, clearly a manufacturing issue. Well, it's got a manufacturing date and serial number on it, indicating that it was produced slightly more than a year ago. However, when I contacted Ryobi regarding a replacement, they firmly declined. I even offered to send it in for them to take a look at, but they showed no interest whatsoever. warranty claims are completely unreliable. Ryobi's lack of accountability and refusal to honor their warranty just puzzled me. How can they be so reckless for something they sold?