Issue with Kidde Smoke/CO detector

Our house was built in 2016. Two story plus basement. We have five Kidde smoke/CO detectors - three upstairs, one on the main level, one in the basement. All five are hardwired to 120 volt supply and each other. About a month ago, one the detectors upstairs started chirping low battery. I replaced the batteries and all was good - for about two weeks. Replaced them again and again it worked for a little while. Yesterday it started chirping again. I got to looking at some of the troubleshooting documents online and it said that this particular chirp/flash code means that the unit was failing.

I go to home depot last night and get a replacement. These new versions don't have AA battery backup but lithium ion internal batteries. Fits the same mounting bracket and has the same wire harness as the old ones. I unbox it and as soon as I plug it in to the harness, it starts blinking amber and repeating "replace unit."

No issue with any of the other detectors. Is it possible I just bought a bum unit from HD, or is it more likely that something has happened to the hardwire electric feed to that particular location?

We do have an ARC fault breaker that is going bad (failing self test and tripping) in our main panel, but it feeds the dining room outlets on the main floor. I can't imagine it would have an impact on anything upstairs.