Iphone5 not getting boot up
My iPhone 5 is not getting boot up. When I m doing ON.... It's getting ON... Displaying apple logo with bright white light in background but it stays for 1 min & again getting restart !! I tried couple of time but fail to start it fully. It's not getting connected with computer in this start up process. I doubt on over size downloading of memory due to heavy files through whatsapp. Before phone get this problem, I was getting frequent reminder to empty storage in phone but before I do it on 1 day morning it got off after full night charging & I tried to ON but getting above problem only. I think it's not getting boot up. I chked it's IC which is also OK . It's battery is also ok. What else could be reason & how to start it again ?
iPhone 5, iOS 7.1.1