The error YOUR APPLE COMPUTER HAS BEEN BLOCKED, Mac System Alert!! followed by System has been infected due to unexpected error! and requests you to Please Contact Apple Care 1-855-680-7080 Immediately! is a fake warning, generated by a adware on your browser/system which prevents you from accessing the internet. What these guys wants you to do is call the company; so that they can trick you into believing them that’s this was a virus and steal your money.
This is a new type of tech support scam.
First Force Quit Safari
1. Press command + option + esc keys together at the same time. Wait.
2. When Force Quit window appears, select Safari if not already.
3. Press Force Quit button at the bottom of the window. Wait.
4. Safari will quit.
Then, 5. Relaunch Safari holding the shift key down.
6 Click Safari > Preferences > Security > Privacy and choose Cookies and website data, Click “Details” button. Remove the cookie related to this, if there is one.