I had/have the same problem. If you go to setting/psn/account information, then sign into email. you should have an "!" mark next to it, saying your email need to validate. Click the validate button, wait for the email, click the validate link in the email (people seem to not do that and think only clicking validate on the PS4 works) After you click the link in the email, go back to the PS4 and click the alrady validated button. This seems to have worked for me and my buddy. Fingers crossed.
I got this fix from a commenter on a website who said he changed to the Anywhere Net+ source on his TV and it actually showed him the PS4 screen, and it was stuck at a validating screen.
Not sure this will work for you. But good luck
Went back to that website, and people are saying that it works for a while, then goes back to not turning on. I think I may just start shutting down till Sony has a fix and not risk it.