Key Fob only works when running

I have 2007 H3 Hummer and the have replaced the plastic shell on the key fob, the remote door lock and unlock now only work when the engine is running. As soon as I stop the engine after a few seconds the fob stops working. Its not the battery in the FOB, doors unlock and lock but only when the engine is running.

Any idea how I can get back to normal without heading down the dealership

That's an odd one. Do the doors lock and unlock with the door switches when the truck is off?

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