why does my phone switch off and does not switch on despite a battery pull?

[AC Question]

a few days ago , my niece changed the password to my Lenovo A238 (4.4 kitkat ) and there was no way to unlock it except factory reset (Lenovo doesn't have forget password) . one day in after factory reset , it started shutting down on its own and would switch with 5 sec press of power button , a day in and then it wouldn't switch on , I did a battery pull and it switched on , I have done cache wipe too. when its switched off it behaves dead , no response to charge or power button (no vibration,no screen lightup) it usually switches on after several tries and many long hours .

I want to know whats wrong , help please .

 

[the tall guy]

Hi, what happened when you performed the factory reset? how did you manage to set up the phone again if you didn't know the password?