2003 Jetta TDI Starting problem
 

I have a 2003 Jetta TDI that has effectively decided not to start. It won't even crank. I tried turning it over and nothing. All the dash lights come on. I had this problem once in the past and was told it was the starter. So I replaced the starter and tried to start it, but the ignition wire started burning and my car started smoking (Again no crank). I know that I have to replace the ignition wire now, however I am trying to figure out what caused this. Any suggestions?