2009 Mercedes C230 4matic Wont start. Brand new battery installed yesterday. key unlocks and locks doors. Key turns in ignition no display lights come up except middle display which is on when car unlocks. Steering wheel isn't locked. Turn key and nothing happens. Checked fuses, they seem to be ok. Could this be a relay or something else??

 

sounds like it could be your EIS, i had the problem before and it was the EIS in my case have it checked.

good luck

 

You say steering is not locked, but if you remove the key does the steering then lock?

If not then replace the ESL,
ESL is a very common failure!
Not the EIS.

 

If these cars dont start, (No crank) 90%of the time it is the ESL (Electric steering lock) related. Get an emulator and remove this cancerous tumor these cars have.