Right now I am just trying to accumulate enough knowledge that I can call him on any bullshit he tries to feed me. Its really a shame I didn't know more about this because they actually sell a vats bypass module on ebay that sends an okay to the ECM to let it start. It costs 25 bucks. it doesn't trip lights and goes beyond just bypassing the ignition reading the key.

Mechanics can be just like doctors... if they don't know something they should they pretend to and if they knowingly screwed something up they won't admit it. But yippy the mechanic says he will be "more than fair" with me with the pricing.

The BCM has absolutely nothing to do with the car running or not. He needs a better schematic. There are not 5 boxes as he states. There is ONE. You can bypass the system with a resistor. That'* my suggestion to you at this point.

My gut tells me you have an inept mechanic.

So what module is he replacing then that would keep the car from starting?

Keep in mind my security light was activated well after I had turned the car off.

Other than the PCM, the only module that can prevent a start is the Vats module. Unless you want to include the ICM under the coils.