Help, updated OS to X but now cant get in

[MacgrrrlDC]

I did a software update to OS X. Got to the screen where it asked me to login in to the iCloud and then my password didn't work. I clicked "forgot" to get password and now it's frozen with a turn wheel on the screen. It won't let me go Back or Continue.

If I try shutting it down, it says "the application Setup Assistant canceled shutdown".

How do I stop the wheel from spinning and move on from this screen?

 

[damidget]

Maybe unplug from wall?

I know, it might corrupt the hard drive

 

[mmomega]

Hold the power button down until the machine turns off.

On another computer go to
https://appleid.apple.com/cgi-bin/WebObjects/MyAppleId.woa/

reset your password

press power on other iMac and go back through the process and enter the correct password.