Why does my iPhone enter into a bootloop after startup?

[Tristan Pointer]

Iphone Enters bootloop after startup

Hello there,
My iPhone got hot this morning on my walk into work. Upon checking it as I arrived at my work it displayed the Apple boot logo.

Next, I performed a hard reset. This allowed the phone to display the lock screen.
However, upon entering the passcode the phone reentered bootloop in less than 5 seconds. The phone is on O2, and has not had any recent water damage or drops.
Suggestions on causes and troubleshooting methods would be most welcome!
Thanks!

 

[gpobernardo]

Re: Iphone Enters bootloop after startup

Have you tried leaving your phone plugged in for about 15 minutes before trying to turn it on again?