IPhone 5S wont turn on after update?!

I updated my phone to 7.0.5 and now it wont turn back on, I don't know what to try and I've only had the phone for like two months!

Please help me:(

Try to hold down the power and home button to see if it restarts. If not, try the same while it's connected to iTunes.

I'd recommend exactly what the other user has said but I'd like to add something. If it still doesn't work I highly recommend contacting apple. I recently had problems with my iphone 5c and I went onto the apple website and was able to live chat a member of staff. They are really helpful

I was doing the iOS 8 update on my iPhone 5s yesterday. I hit the install button now all I get is a white screen with the black Apple icon on it. I can turn off phone by using the power and home button. When turn phone back on still same screen. When hook up to computer and go on iTunes it won't recognize my phone.