In this case Nothing will work if you keep trying..

Try this:
1.unplug your tv. (totally disconnect power supply)
2.After 10 min plug the power supply back.
This worked for me and I hope works for you too.
Remember: Unplugging makes all the difference here. on/off with remote wont work.
Hi there
I have had this problem as well. Spent ages on phone with Google and – noting that they were very helpful and called back several times with additional suggestions – they finally agreed to replace the Chromecast. When the new one arrived I had the same problem!! This thread has been great and I worked through several suggestions – so thank you everyone for the very clear instructions! This is the one that worked. (I am sorry for those who gave up after long efforts – if we had found this first it would have been great! So – hope this helps someone.)
Possibly important notes:
- My Chromecast is a version 2.
- I had slightly different results with different HDMI Ports (there are 4 on my TV – some just said ‘check signal cable’, one seemed to want to start the loading process then went to a blue screen and wouldn’t come out again, and one would display ‘Chromecast’ across the bottom of the screen and then the G would form, but then disappear and go to the ‘check signal cable’ message.
- I tried restarting the TV in several ways – turning it off and on, powering it off and unplugging the power cord, pulling the power cord and relogging it after a minute or so.
- I tried restarting the Chromecast and resetting to factory settings (hold the button for 30 seconds or so until the light works through several modes and back to steady white).
- My TV is about 10 years old – Samsung LA40C650L 1MXRD
Specifically, what did the trick was unplugging the TV while it was powered on, and leaving it for the full ten minutes as suggested by shreyans khard.
I restarted the TV with the Chromecast attached to the HDMI and powered through the USB on the TV. Voila!! It worked – I am set up, the Chromecast has updated and I am watching Netflix!