Security system will not shut off and car will not start

I looked your security system, it said starter motor disable. It will probably also disable your fuel injectors. If security system has a problem, you may need a scanner that can communicate with your security system. Also, sometimes when battery voltage is lost, some modules may need to be reprogrammed. Are there any applicable trouble codes?
You can check the basics, spark at the plugs, proper fuel pressure, compression.

I have the same problem few days ago, and still didn't find any solution. Can any one please help?????8

A common problem on GM cars and trucks, especially grand ams (unfortunately) is the security system. They can actually close off fuel to injectors and turn off starters. I wonder if this might be your problem. Is there a light on your dash that says security when you put your key forward to start? If that light stays on, its the security system. Heres a link to a site with tons of info on it, and some solutions. Hope this helps. http://vatspasslockpasskeysecurityhelp.yolasite.com/

The security system will not shut down the car while running, if the car shut off while engine was running you may have another problem. Do you have a "chip" or black pellet in your key, if so the wires going to the key cylinder may be broken at the cylinder or the key may be worn if you are having a security problem

test fuel pump pressure seems like its faulty i think your right

sounds to me like you better find another dealer or possibly an auto electric dealer they should have done it right the first time

If it wouldn't start, you have to see if you are missing fuel or fire. Could be a bad sensor, or a bad fuel pump, or if the security light is blinking, a problem with the security system.

sounds like you need a new alternator.the battery light is triggered by the diode trio in the alternator. if the light comes on.99 times out of a 100 you need to have your alternator replaced.have your charging system checked first. most parts stores check them for free.with the engine running it should be around 14.5 volts.

We had the same issue with our 2007 Yukon Denali XL. Died on us twice after sitting for short periods of time; once we watched a DVD with the engine off and battery died within 10 minutes. The dealership kept it overnight to troubleshoot why the battery died so quickly. They said the radio was "pulling" too much from the battery. (They supposably fixed it) But again a few days later the battery died again after sitting overnight. We brought it back to the dealership and they brought in a GMC "expert" to replace the entire DVD/CD/Navigation system. They also replaced our battery with a much larger battery, similar to the ones that GMC puts in there diesel trucks. They had our Denali for 5 days, but it appears to be fixed now.
Getting it fixed correctly wasn't without headaches, but it was all covered under warranty, including the battery. And they are updating the nav w/ the new edition disc as well for no charge.

loosen the battery cable.... start the car with a boost.... after it is running... unhook the battery.... if it dies... replace the alternator... if it keeps running... replace the battery.... make sure this is done outside and everyone working on the car is wearing safety glasses