2004 Mercedes Benz SLK320 6 cyl Two Wheel Drive Automatic 47842 miles

recently we had left the interior light on and the battery had died.
when opening the car i put the chsager on and the alarm when off. manage to shut it off.
I had reset everything eles.
But now the radio does not work.
Manual says when i turn on the radio the word code will come on.
but i get nothing when i try and turn it on.
Thanks
Kevin