cae wont start. mileage has zero'd out

It sounds like the body control module went bad if the mileage went to all zeros that could be the reason for the no start.Also if the body control module goes bad you wont be able to talk to the engine computer ethier.You need a professional scan tool to talk to the body control module. A diyer scan tool or free code scan at the auto parts store wont read the body computer. So is the security light on solid or flashing with the key in the run position? With the 2 second run sounds like security is keeping it from starting.There anything else not working correctly?
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It blinks then stays solid, but since then weve replacsd the bcm, it doesnt rearm itself ,but it still starts and dies. We've checked and cleaned all the dirt and rust off the grounds under the hood, and are looking for a possible short in a pcm wire, or replacing the cam sensor, everything, but the engine running, is good.

Did you put in a used bcm or new bcm?