iPhone 4S won't turn on, just flashing Apple logo

Hello!

I turned my iphone 4S off as it wasn't receiving any emails.Then I turned it back on and now it just flashes the Apple logo at me!

I've looked on other forums and pressed the home button and sleep/onoff button together for 30seconds. Nothing happened.

So, I connected the phone to my mac and restored factory settings. Still nothing worked.

It's still flashing the Apple logo and I have no idea what to do.

Can any kind person help please?

Thanks!