Why is my Mercedes 300 is completely dead and won’t start

What is your question?

I tried to unlock my car door and the door wouldn’t open, so I changed the key fob battery. Open the car door and nothing came on in the the car(No door lights, radio and etc). I drove it 2/12 week ago and their was no problem at all. There’s no noise, it’s just completely dead

What makes this problem better or worse?

First problem with this car

How long has your 2012 Mercedes-Benz C300 had this problem?

I havent