Do you have a second key that does unlock the doors?
With the Skreem module allowing it to be driven I would say that the key is emitting the correct frequency.
I had a similar issue slightly different and it was my CLP/SSM.
Have you taken a look at the CLP/SSM? To ensure that no water damage has occurred?
When my CLP/SSM was damaged my locks would still lock but my lights would not flash, my fog lamps and map lights would not stay on after exiting the car. It is strange what corrosion will do to electronics. I too started with the siren and then found the CLP/SSM issue.
After I repaired my CLP/SSM and my siren everything worked as it should.