My MacBook Air got stuck in set up, after leaving it hanging with the beach ball for a good 2 hours I forced it to shut down. Now it won't restart and I'm getting a 🚫 On the screen after it tries to boot. Any solution?

Yes. Or you can return it while under warranty and let Apple deal with it because it is brand new. But do this ASAP. Please make an appointment at the Apple Retail Store - Genius Bar and take it in for service. If you are not in the USA or cannot set up an appointment this way, then contact your local Apple Store directly.

Mac OS X- Gray screen or prohibitory sign appears during startup

Install or Reinstall OS X from Scratch

Be sure you have backed up your files because the following procedure will remove everything from the hard drive.

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears.

Erase the hard drive:

1. Select Disk Utility from the main menu and click on the Continue button.

2. After DU loads select your startup volume (usually Macintosh HD) from the

left side list. Click on the Erase tab in the DU main window.

3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on

the Security button and set the Zero Data option to one-pass. Click on

the Erase button and wait until the process has completed.

4. Quit DU and return to the main menu.

Reinstall OS X: Select Reinstall OS X and click on the Install button.

Note: You will need an active Internet connection. I suggest using Ethernet if possible

because it is three times faster than wireless.

This should install the version of OS X that you had installed.