4matic problems

What is your question?

I got a 2005 Mercedes c320 4matic it's been sitting for about a year the battery went dead and it's been on a trickle charge ever since I went to go put it together today and noticed the front wheels are spinning freely even though it's a 4matic I started it put it in gear and I was able to stop the front wheel with my hand what would be wrong with it