@daveva 

3-way switches essentially break the function of a single switch into two separate switches.  For the lights to be independently controlled by each switch, extra wires (traveler) are needed. These extra wires are how the switches communicate with each other and lets the other know when the lights have been trigger on/off.  One switch controls is connected to the power and the other to the Load.  This is why you need two switches.  With TP-Link's 3-way dimmers there is the added feature of controlling the voltage which is how the lights dim or brighten.  The way this is achieved makes it impossible for our switches to be used seperately or with a dummy/existing switch.  

For your particular concern I am afraid I don't follow.  You say the switch doesn't provide power but that the buttons on the switch work.  Can you explain in greater detail?

  @daveva 

Warranty coverage depends on the region you are in and the product you purchased.  Here in the US smart switches like that have a 2-year limited manufactured warranty.