Toyota Aqua/Prius C Not Switching To Ev

Hello Guys, I am fom Pakistan. The Problem which i have with my Prius C is that Its Ev mode is not working and the engine is running all the time.When I start the car it starts normally but when i shift the gear to D the engine kicks in automatically,even if the battery is full. When the gear is set to P then it switches back to Ev.I have changed the hybrid battery but it was of no use, then i changed the inverter, the blower of the battery but still i am facing that issue. I dont know what to do now. Kindly Guide me. There is no check light in speedometer.