Will pushing on a car always change the car's mechanical energy? what must happen for the car's kinetic energy to increase?

push is force. force changes momentum. momentum linked to energy.

yes

car must be accelerated by push

when the use of electricity burdens the fuse and miniarure circuit beakers and there is a possibility of a fuse then they automatically cut off the electricity supply to your homes and after you fix the problem u jzt switch it on and it continues the supply of electricity to ur homes

probably not if net force is zero