The new battery might be faulty – test with a different new battery.
Device Doesn’t Recognize the New Battery: You can try waiting for the device to recognize the new battery, or perform a hard reset to clear its memory.
Dust Blocking the Detector’s Sensors: Dust can accumulate on the sensors of a smoke detector, causing them to trigger false alarms. Wiping the sensors clean can help resolve this issue.
Corrosion and Leaked Chemicals: Over time, batteries can leak and create a flaky residue that interferes with battery connections. Cleaning the contacts and replacing corroded batteries can help resolve this issue.