So I just finished the rebuild of my '98 Neon DOHC, and so far only oil is in it. After many problems, it was finally time to start it. Ran great 3 times. 4th time I tried to start it, a massive spark jumped between the positive terminal and the drivers side body. Visible arc between the 2. The whole system went dead, no dashboard, dome light, radio. 3 seconds goes by and suddenly every light in the car starts flashing randomly, no patterns to it, just flashing like cheap prop in a b-movie on late-night. I dashed to get tools to unhook my battery but in the 30 seconds it took to get back to the car it stopped happening.

All sensors were plugged in, just no coolant and no belts to alt or p/s and a/c. Now it doesn't do anything when I try to start it, no guages either. Unfortunately I had to leave for work so I wasn't able to look at anything yet but google has been no help, partly because I just don't know how to search this problem.

So can anyone please take a guess at what may have happened here?

*EDIT* I should also add that the "key dance" showed no codes beforehand, not even the no codes code.

*EDIT* a video of someone else's car (another model entirely) doing this.
http://www.youtube.com/watch?v=t-zCXqCwNDw

 

A couple things can cause this.1 bad grounds 2 bad cell in battery 3 no signal from alt

 

You were right, 1tonpig. I cleaned up every ground surface there was according to another thread using search. Oddly the battery held 12.6V when I checked it later, without charging it after the mega-spark. All problems cleared up. Thanks for the advice, and I'm glad it wasn't the alternator.