Despite there being many reports on this forum of this device stopping working due to poor quality hardware, the manufacturer is dodging the bullet by making the support route awful. 

 These devices stop working because of a poor quality relay that "breaks" or "sticks" leading to the unit not powering off. As a result people will either put it in the bin causing e-waste, or ring support and again have an awful experience.

  After being asked pointless questions like who is your internet provider (Really that has nothing to do with the issue), what is your email address (just diagnose it FIRST befoire adding me to your marketing database) and putting people through pointless trouble shooting (I have 40 years product development and support in IT & Telecoms) they then say OK the hardware IS broken and you need a replacement. What's your email address we'll get the replacement team to contact you. Then they try to send you to Amazon (hint I didn't buy it there), and then if you don't have your receipt you might not get a replacement. Why can't you confirm that BEFORE sending me on a pointless email journey ? Err no. I can't. I only take the calls. That's a separate department. OK why don't you contact that department and check whether they will accept your confirmation that the relay in the product is broken and irrespective of whether its in or out of warranty just do the right thing and say your product was a poor quality build and you will replace it free immediately. But no. Can a manager call you back to discuss..... Well OK if you must. I am awaiting that call.

In the meantime I read this thread and remember back to the days when working in IT support at a PC manufacturer. Customers would ring up and say the hard drive had failed what could we do to fix it as they lost all their data. We told them to lift the front of the PC up by 2-4 inched and drop it. It would immediately make the hard drive work so customers could retrieve their data and then get a new drive. We would then arrange a warranty repair because the quality of the hard drives in those days was shocking. Buit that was a manufacturer who looked after their customers not one who sells poorly tested junk.

So what did I do ? I slammed the piece of e-waste P110 on the desk as described below and guess what. IT WORKS. For how long is anybody's guess but I won't be buying TP Stink products ever again. 

https://community.tp-link.com/en/smart-home/forum/topic/640098