Purchased four, four down! Normal operation for one minute, and then issue an alarm indicating a malfunction (two beeps every 45 seconds). By following the advice of the record, simply vacuuming on the device, but it does not change the behavior of the sensor. The battery does not seem concerned. No repair possible since the date of return is exceeded at Amazon. No interest to make a reference to the manufacturer warranty penny in Britain, shipping cost more than the camera. Product unreliable to boycott! Information circulating on social networks, I'm obviously not the only one to have made myself! Amazon thank you for the bad quality of products sold!
