logitech k400+ keyboard function test to samsung smart TV 

Insert properly the usb of the keyboard to back panel of the tv, check the setting set up of your tv, the keyboard has switch on off make sure to activate. In the smart tv screen it will appear pop up ALLOW external or others then click ALLOWED. hope you configured .thnk you

Please watch the video In my experience as of now you can Power on the TV using f12 & ins keys.