Why won't my phone turn on?

[Windows Central Question]

I was updating my Nokia Lumia 520 and it took a long time. After the process of the little white gears turning, it shut off. I turned it back on and it keeps going back to the white turning gears and shutting off. I don't know why and it's really annoying me, I need this phone for business really bad. Help?

 

[realwarder]

You may well need to run the Windows Devices Recovery Tool and restore the OS. Hopefully you made a backup before upgrading in which case getting everything back again should be easy as you can restore the backup during setup.