My 4S was fine before I started the update (believe it was the 8.1.1 but not sure anymore), five minutes after starting the update, I went to check on it and it was looping between the Apple logo, a horizontal line, a white screen then back to black and the logo. I have tried the resets, connecting to iTunes and every other thing I could find on the internet. I have finely been able to shut it off, after disconnecting from power source and holding down the home button and sleep button for several seconds. As soon as I turn it back on or plug it in, the loop begins again. I really need my phone back in working order. Any suggestions?