LL2385

Hi there We have a smoke alarm in the kitchen that has been chirping every few minutes for a few days. We have just changed the batteries (it’s mains powered too) in all three of our alarms in the house to no avail. When the mains is off, and the batteries are out it still chirps from the base in the ceiling. Absolutely no other alarm in the house whatsoever. I pressed the test button on each alarm after replacing the batteries in each. Any ideas? Thank you Laura