Press and hold the test/reset button for 15–20 seconds
If it is a hardwired unit, turn off power at the breaker first
Remove the detector from the mounting bracket
Disconnect the power connector if it is hardwired
Remove the battery
Hold the test/reset button for 15–20 seconds to clear residual power
Reinstall the battery
Reconnect the power connector
Reattach the detector to the mounting bracket
Restore power at the breaker
Press the test button to confirm it is working
Replace the detector if it still will not reset or keeps chirping