@igvaram 

You may have broken the device. The device should be powered on all the time during the update. 

Edit: Found the manual and notice that the blinking green indicates Camera updating. Perhaps you can try to leave it for a while and see if the update can still processing itself. 

  @Riley_Blue I leave it for a dey, but not doing anything, only blinking green.   when I turned off wifi, is started blinking red.

  @igvaram I encountered the same problem. Unplugged the camera and didn't know it was in middle of updating. 
 

have tried everything, resetting so many times. Camera is showing in Tapo App as offline. Tried to remove from app but still keeps on showing up again even if removed. Deleted app from phone and all data. Reinstalled app again, camera shows up again as offline. Tried to connect to different network -both via wifi and Ethernet. Now trying via Ethernet, just keeps on blinking slowly with green light. Will keep it on for several hours and see how it goes. 
 

hope someone from TP Link support sees our problem.