Downloading...Do not turn off target. How to fix it

[AC Question]

android picture and "Downloading. ...Do not turn off target" stuck on home page. How do I get it off?

 

[Rukbat]

If you're flashing a ROM, don't turn the phone off, otherwise turn it off, then on again. (If you don't know if you're flashing a ROM, you're not.)

 

[B. Diddy]

Welcome to Android Central! If you're not sure how to reboot the phone from that screen, let us know which phone you have first.