Programming PCM

More than likely you have to program the wireless control module to the PCM now. When you plug in a PCM that is already programmed it will tell the VIN to the other modules. This will confuse things and when you installed the old PCM it is no longer "sync" with the WCM.

If you are able to scan for codes that should tell us what the issue is. There could be other issues but the codes will tell us for sure.

Unfortunately the battery was disconnected when i swapped the old back in and code reader wasn't picking up anything. Should i maybe try a hard reset?

How do i go about reprogramming it?

You have to hook up the scan tool capable of doing this and follow the procedure from the tool to program it. Basically you run the PCM replacement function. If all you did was plug in the other one then I suspect the VIN mismatch is the issue.

You may have to replace it with a new one at this point. Unfortunately you cannot swap PCMs on these vehicles. They store the back up info for the security system and if that doesn't match, it locks them out.