This problem happens bcoz of current fluctuation, hope my few steps help you solve this problem.
first you need to remove battery. then hold power button for 30 sec to 1min.
then connect power cord then press power button. hope it will works.
then make sure your power cord is in working condition, if it works fine then repeat the steps as i said, this time you need to hold power button for 2 min or more, Note :- there should not be any power supply when you are doing these steps.
thanks & regards