iPhone 6 problem need your help
Hello everyone, i recently bought an iPhone 6, and now i have a problem with it. The phone works perfectly but when i lock the screen it shutts down after a period(1-2minutes), and to power on the iphone i need to press the lock and the home button at the same time, this is happening when i lock the phone, to avoid this i need to set the autolock to never from settings. What could be the problem? If i connect it at pc it works ok(no shutting down issue). Thank you.
iPhone 6, iOS 8.1.3