1999 Mitsubishi Eclipse

I jumped start the dead battery in my mitsubishi eclipse '99 and I made a stupid mistake.I connected the negative end of the cable directly to the dead battery. There was a spark on the dead battery and I saw a little smoke that came out from the radio. The car didn't start at all when I cranked it.I immediately removed the cables from both batteries and I noticed that the cables is kinda hot. Please tell me what could be the electrical damaged in my car. Been out of job for few months now and so afraid that I won't be able to afford to fix the damaged.I really appreciate your help.