Car acts like there is no battery

I don’t think is the alturnator . It could be the sensor control panel ,where all the sensor switch is located behind the relay box . The car computer pick up nothing from it , so nothing can happen

Check the main fuses, in car,ECM,

I checked the two main fuses and they are ok, where is the relay box located

Under hood,

Check the ignition switch by connecting a voltmeter on each wires with ignition on for accesories. Then check voltage on ignition on for power. Make sure the ground is connected to something metallic when checking voltage.

I changed the altinator, still no voltage going to the battery, where is the generator relay located.

Check the sensor control panel which is under or nearby the relay