Hi Brian the same thing happen to me so , first you would have to put it into recovery mode. You have to connect the apple cable to a computer and open itunes. hold the power button and home button for about 10 -15 seconds and do not let go when you see the apple logo. stop holding the buttons when the itunes symbol and charging wire symbol appears. then go on to itunes and click on your phone. there click on update which will help it boot up. if it doesn't work press the restore button which will work most of the times but deletes all your data but works perfectly.