Thank you for providing all the details about what you have tried. That helps a lot. Solid white means that the Chromecast THINKS that everything is working perfectly. Obviously, it is not.
The hard-reset should have put it back into setup mode, the light should have changed to flashing white, and you should have seen SOMETHING on the TV about needing to be setup again.
If that did not happen, something is very wrong with your Chromecast.
One more question, what does the Google Home app tell you about your Chromecast? Does it say that everything is OK and show you that it is in Ambient mode with the pictures changing?
The only other thing I would suggest is try a different power-block and power cord (never plug it in to the USB port on the TV, those often don't push enough power for Chromecast devices). There is nothing special about the blocks and cables that come with the 2nd Gen Chromecast devices. Just about any ones you have around the house will do.
If nothing changes when you do that and if you cannot get it to reset then you are probably stuck and will need to replace the Chromecast device. I'm sorry.
