International DT466E won't fire
 

So we have a '98 international 4700 boom truck, built by auto truck in Bensenville, IL. It has the DT466E in it. And the laborers working out of this truck left the lights on and drained the battery, then took it upon themselves to replace the batteries. They hooked up the batteries backwards, then called me when it wouldn't start, just kept cranking. Now that the batteries are hooked up right and charged it still won't fire. I noticed the positive post on the alternator (new last year) burned loose. But even with jumper cables hooked up it still won't fire. I plan on changing the alternator first, but does anyone know if this situation could have damaged the ECM, HPOP, injectors, etc. Or why it won't run?
Any help will be greatly appreciated.

I hate to say this, but you really need to take it to a pro.

If you have it turning over but not firing, and the reversed polarity was severe enough to melt an Alternator post, then there is no way of determining how bad other things got fried, just that they in all probability did get fried bad. When you first turn on your key, do the gauges go thru their self test?

Yes the gauges do, they run all the way up then down, but I get nothing when I push the engine diagnostics button for the flash codes, no flashes at all. I am trying to locate a qualified service tech, but we are almost 3 hours away from a dealer.

Check your ecm fuses. Chances are they are popped. Also look for the main charging fuse, I can't remember where it is on that generation, but it was a maxi fuse, last I saw.

I think you'll find your problem there, the reason being, all fuses for ecm protection are generally 5 amp or less. The fact that it does a gauge and light check, is positive.

On edit: some of those ecms also needed to "see" all electrical components, during the self-test procedure. Happens during the gauge and light ping. If something is missing, they simply will not work. ( such as the alternator)

Good luck