Battery Capacity Dropped Significantly with New Battery

I installed a new battery from iFixit in January and was working fine until recently. The battery indicator on the taskbar showed both full, and red, with a warning to plug the computer in. coconutBattery indicates the design capacity is 9% of what it should be. I didn’t check when I installed it but it didn’t seem to be a problem until recently.

I have already done a NVRAM reset and a SMC reset with no changes. Any ideas? Has the battery failed on me? (It’s been less than a year, I expect it’s still under warranty.)