Powers up, then shuts down
Hi there guys
I have here an iPhone 5S that does something rather strange. I have recently refurbed the whole phone with new components, inc battery and screen.
The phone powers up, shows the Apple symbol for about 2 seconds then the screen goes blank, however you are able to see the lit up backlight. It stays on for about 15 seconds then shuts down, any ideas of what it could be?