Can't tell if I got a bad starter or battery. Took it to the shop to get a resonator delete and when I went to go crank it up it cranked once but doesn't start so I cranked it again I didn't get any cranking sound Or anything so basically no start just the lights on the dash with no errors at all.!.. the mechanic said it's a bad starter but how could it possibly be if it's been fine before bringing it into the shop ... like I had it for 3 months running perfectly until I brought it in ... any suggestions?!? I have a 2003 c230 k

 

apply voltage directly to the starter---what happens??

 

How old is the car?
Quite likely the starter needs new brushes if it's over 120K miles.
Just because you repair something one day doesn't mean something
else won't break the next day. I say this from experience.