Repair problem

HI, I have an iPhone 6 Plus currently using the latest version of iOS 9.3.3, my iPhone keeps rebooting when it's idle, the screen show lines n to get it on I have to press tight on the screen then play music when it finally completes booting,can anyone help. I have to play music in order to keep it on even when am not using or asleep. It's frastrating n it's the only one I have.