Why won’t my car start?

Question. I have a 2011  Mercedes c300 with
about 110k on it and it won’t start now.
Battery is 90% but when you put the key in, it
automatically says remove key. And when you
try to turn it on you hear the different clicks
but when you’re on the last one to start it
nothing happens and no sound happens.
Does anyone know what it could be?? We’ve
already checked the fuses and changed out
the esl. But I’m stumped at what I could be.
The car locks and lights go on. It just won’t
start. Please help