Replace the battery immediately
Check whether the detector has a sealed backup battery that needs replacement
Press and hold the test/silence button to stop a low-battery chirp temporarily
Reset the detector after replacing the battery
Clean dust and debris from the detector
Verify the detector is fully seated on its mounting plate
Check for end-of-life warning and replace the detector if needed
Turn off power to the hardwired detector at the breaker if safe to do so
Replace the entire unit if it is expired or malfunctioning
Contact the manufacturer or a licensed electrician if the chirping continues