Review on Wireless Interconnected Combination Smoke and Carbon Monoxide Alarm with Voice Location - First Alert SCO501CN-3ST, Battery Operated by Rick Everett

Two of these detectors have worked well for 6 years and one eventually went dead and had to be replaced. I bought two identical SKUs, but there is no "OneLink" on the front of the device. As before, when trying to connect two devices, I had no luck. In step 4 of the instruction, the 1st block (already configured) does not cause the green light on the 1st block to go out as described. It just goes into test mode without affecting the 2nd block. The second block can be configured and operated independently. I have two apparently working CO alarms and a smoke alarm but there is no communication between them so I bought them. I have two units in inches apart so distance isn't an issue. I tried binding in the opposite direction with no difference in behavior. I don't know if I have bad blocks or not. And if only one is defective, I cannot say which one. I contacted BRKEelectronics (who now make this unit) and they confirmed that at least one of the units was defective and sent me two replacement units. I will update this once I get a replacement. The two replacement devices arrived within a few days and work great. I am updating my review due to the excellent customer service.