How to turn my iphone 4 back on after updating it to 6.1.3 and it was jailbroken?

I was updating my iphone 4 to the new update (6.1.3) and it didn't work so it told me to restore it but then it turned off and i'm really scared please help!

Hold down the home button and power button for 10 seconds then release the power button whilst still holding the home button, you should enter DFU mode, (that only means your iPhone is in recovery mode). Hold down the power button until you see the apple logo and it should be fixed!