Review on Hardwired Kidde Smoke & Carbon Monoxide Detector with Lithium Battery Backup - Interconnect Combination Alarm with Voice Alert by Rafael Gomez

I ordered 4 of these to replace 4 old Kidde alarms that were nearing the end of their life. They use the same wiring harness, so installation should be easy. It was not; there were three main problems: 1) alarm clocks have a switch on the back; The first installation step is to turn them on with a screwdriver (or the plastic tool that came with it). One of them has already been recorded. There was absolutely no indication that it had been previously opened and returned; The packaging (which is unsealed) looked the same as the other three, and the plastic tool was still taped to the instructions. When I installed this, it immediately said "replace alarm". 2) The other three do not work according to instructions. The green LED ring should glow when the alarm is plugged in, letting you know it has power. I plugged them in and nothing happened. I plugged in one of the (old) alarm clocks I'm replacing and the LED lit up. With the new alarms, if I turn off the battery and turn on the alarm, it beeps and the LED lights up (indicating it has power). After one second, the LED will go out and never come on or blink again. 3) These alarms have a large bulge on the back, unlike the old ones; This bulge protrudes about 3/4 inch back into the junction box. If there are wires in the junction box, you may need to remove the alarm's mounting ring and move the wires around the sides to make room for the bulge. Do this with all four of me.