I wish I coulda chimed in sooner, it's Definatly a immobilizer issue, once ur battery went dead, ur alarm had some issue with recognizing the rf ID pill inside ur key fob. That Sorta thing happens time to time with porsches that are garage queens or weeknend cars cause the batter will die out sometimes at quick as 3-10 days depending batter condition & draw the batter has on it from any anti-theft that require power to operate, sometimes immobilized will fail in those situations as well and have gotten several cars in for the same reason but we always have to refer them to the dealerhip cause only they can correct Porsche Anti-theft equipment.
But u did good on ruling out any possible reasons it could have been which is what most of us would have done as well... Until our patience has absolutly been drained.
