I purchased a 2 switch kit from Amazon in January of 2020.  I used one of the switches.  It worked fine until last month at which point it was froze "ON".  I removed the faceplate to inspect the wires and they looked fine.  I tried 3 times resetting and reconnecting to WIFI and was successful in reconnecting all 3 times but when I clicked the button to turn the switch off nothing happened and when I clicked the button in the Kasa app nothing happened.  I did see a spark come out of the screw where the line wire was connected so I decided at that point to replace the bad switch with the other one in the kit and it works fine now.  I asked TP-Link for a new switch to replace the defective one and they want me to ship them the entire kit (both switches) back.  That is crazy.  I am not going to waste my time uninstalling a working switch to get them to replace my $20 defective switch.  Fortunately Amazon now sells other brands of wifi switches so I am never buying another TP-Link product.  So long.  I only wish I could return my Deco wifi routers as well.