mobile switch off automatically

[AC Question]

after switching on my mobile and getting to the home screen (after device is switched on) my mobile automatically is switched off(direct off where there is no switch off conformation nor any vibration ) when i gave a closer look this switch off happens when my device search for the cellular ie mobile network...then i turn on flight mode and my device runs smoothly....then i turned off my flight mode and like wise when device began to search for cellular networks it switches off.....I NEED A WAY TO FIX IT....PLEASE HELP.....i am using Micromax A210(canvas 4) model
Thankyou