Nissan Repair: 1990 300ZX wont start, local wrecking yards, selenoid

Question
i have a 1990 300zx non TT. i accidentally crossed the wires when i hooked it up to the battery. ever since then the car would not start.  i thought it might have fried a section in teh power wire, but i checked and the wire is fine. i then went on to the selenoid on the starter. unfortunately i could not test the selenoid seperately from the starter. so i had the whole thing tested... when they ran the test nothing happened except a little humming/buzzing sound.. i assumed either the selenoid or the starter was bad so i replaced them both. after i replaced it i got a new battery to make sure i had full power and i hooked it up. when i tried to start it all it would do is make a loud and fast clicking sound... however, when i replaced the starter and selenoid i did get power back to the rest of my car. before i had done so, no power was getting through to anything, no dash lights would come on, nothing at all would work. now when i try to start it all of the lights and electronics cut out when i turn the key all the way.. i really do not know what is going on with it.. thanks, josh

Answer
Joshua,

Now that the starter has been replaced I would check the computer.  The ECM computer that drives the car is probably fired too.  So, check to see if you are getting fire to the plugs and injectors and if you are not then replace the computer.  Go on ebay or check with the local wrecking yards or check with your local Nissan dealer for the cost or a rebuilt computer.