Strange symbol when trying to turn on phone

[WPCentral Question]

I have a Nokia 625, i have recently ungraded to Windows 8.1. When i attempted to turn my hone back on a logo appeared on a black screen of a big lightning bolt next to a small systems cog. anyone have any idea what this is and if so if it is a problem?

 

[Guytronic]

That's a phone reboot problem.
A soft reset may fix it.
(off button-volume down pressed and held together for 10 seconds)