@Dzei I just had the same thing happen. I have a bunch of these. This set was the most recent ones. They had been working for 3-4 months. Tonight one switch just started switching the lights on and off. 

  @Dzei I have the same problem after 14 month of the switch working perfectly.  Did you find a solution?

  @Dzei  I have the exact same scenario that I noticed just a few days ago. HS200 that's been working fine for more than a year is now exhibiting the same behavior that you've expressed. Any updates from the company? 

  @Tom1166 

All, no solution, no communication from corporate.

  @Dzei same issue here with 2 out of 20+ switches suddenly stopped working. Both of them that died are newer, I have some of the older ones that are larger and they have been fine for a few years. I can return the faulty ones under warranty, but it's cheaper to buy new ones than to pay shipping to send them back. I'm pretty annoyed with it, since buying new ones seems like I may just get bad ones again.

Same here.  HS-200 been working fine for over a year and suddenly was flashing green.  Reset button just turned "off" the switch, but it went back to blinking green only.  Trying to manually turn on/off lights make it rapidly click and flicker the lights.  Had to repeatedly press the button to make it stop. 

Based on the replies here...I didn't feel like an answer was coming soon, so I replaced it since I didn't want to kids to accidentally press.  New switch working as intended including firmware update upon install.  

  @Dzei So after looking at a few similar posts, including ones with premature failures on kasa smart plugs as well, it looks like the problem is some bad capacitors that were used in several of their devices for a while. I popped mine open and sure enough, both of the ones that stopped working had bulging capacitors. Looks like the bad caps are 470uf 10v. I bought some from Amazon for 8 bucks for 20, so I can fix my 2 that stopped working and have plenty of extras if any more die (both of the bad switches were from a 3 pack, so I'm sure the other one is going to go soon too). I'll report back after I replace the caps, but from what I'm seeing I can pretty much guarantee that's the problem. I can't link the ones I bought apparently, but they are 6.3x12mm, which should be the same size as the original for those that don't mind some light soldering.