I just began to update my iPhone 6 with the new iOS update. Now the Apple logo appears, then a red flash occurs, then it goes back to the Apple logo - and is stuck in a LOOP!
You can boot the phone into recovery mode and then connect it to your pc / mac and have itunes recover it. This will wipe all your data though. To put it into a recovery;
1. Open iTunes and connect the iPhone to your Mac. ...
2. Press and hold the Home button and the Sleep/Wake button at the same time. ...
3. As soon as the screen goes black release the Sleep/Wake button. Continue holding the home button until you iTunes pops up a message telling you that it has detected an iPhone in recovery mode.