So, the mobile tech ended up replacing the cinching actuator and cable and the liftgate latch. Out of warranty would have been $511, but I only had to do the deductible for the extended service agreement / extended warranty ($200). The tech was very happy that I was able to get the liftgate up before he arrived (it adds about an hour to the repair if the liftgate is stuck down). He told me a story about going to fix a 2012 Model S with the same problem...the owner had the liftgate up and then closed it to demonstrate the problem, of course it got stuck in the down position ("Noooooo...").
Anyways, all systems operational once again.
Bruce.