How to cancel an apple update?

I was given a notification that i can update my Iphone 3GS to IOS6.1.3, so i pressed "update". My Iphone turned off, then began rebooting, and is now at the black screen with the white apple logo page, and doesn't go any further. It keeps going black, then coming back to that screen. It has been about 30 minutes with no progress. What should i do about it?

Thats hard to say. I would not update a iphone 4 or lower to IOS6.It just makes it run slower. I'm not sure.Id say hold the home and top button to see if it reeboots but i don't know if the softwear will work. Try it as long as your phones backed up on your computer.

hold the buttons together for about 5 seconds.