Asus India — phone keeps rebooting itself

Address: Bangalore, Karnataka, 560069

I have an asus zenfone selfie 1st gen. I bought it 2 years back from amazon for 14, 999. Since the beginning i have been experiencing one or the other problems on this phone. The device kept heating up constantly. A few months back the phone started a factory reset by itself resulting is a lot of my data being lost. Now the device has entered reboot mood and has kept itself in that state for more than one day. I can't even switch off my phone without removing the battery. Please help.