Oh, I understand this. However, my annoyance with the electric top overrides my concern for selling to the next guy. Thankfully, the modification seems totally reversible.

Just to update this, I ended up taking the car to my indie to diagnose the top. He was as stumped as I was and everything seemed to be working. A new relay didn't even fix the problem. He ended up taking it to another shop who discovered it was a fault in the alarm control module. They were able to reflash it or something and now the top works as expected. Bizarre.

Follow up #2. Oops! Top stopped working again. This time stuck down. And the Porsche continues to be the least reliable vehicle I've ever owned (Shocking when that list include a rotary-powered Mazda 15 years older with twice as many miles, a Merkur XR4ti, and a handful of 90s Fords).

I've gotten as far as dropping the windshield header microswitch assembly, but I cannot for the life of me disconnect the switch itself from its wiring. The connector does not seem to budge. Has anyone encountered this? Help?

Another update:

So I managed to get the microswitch assembly out and tested the continuity of the two switches in there. The first-detent switch didn't seem to be working. I noticed the soldered contacts were pretty corroded so I scraped them off a bit. Got it to the point where it was registering on my multi-meter when the first switch was activated. Put the switch back in the car and....surprise! The top began to function. I have a new switch on the way, so I'll probably keep it as a spare until this one starts acting up again.

FINAL UPDATE I SWEAR.

Old switch worked...then didn't work, then worked again. Ugh. Thankfully, the new switch arrived early so I installed it and, fingers crossed, things seem to be working just fine.

For posterity:

If you are experiencing top failure to open or failure to close and when you pull open your top latch and the following is true:
-Windows go down normally
-E brake light is illuminated on the dash
-All fuses are in good condition
-Top relay is known to be in functioning order

It could very well be the microswitch in the windshield header that has failed even if your windows go down when you unlatch the top! I got off on the wrong track because I assumed that if the windows dropped, the latch microswitch must be OK. Remember that there are TWO microswitches in the header latch - one to drop the windows, and the other to send signal to the control unit that the top is unlatched/ready to retract. In my case, it is evident that the second microswitch or one of the soldered connections in the assembly failed.

Thank you for letting us know what ended up being your problem. I hate when people start a thread and don't let people know what ended up being the problem.
On that note, I converted to a manual top and love it. There's an in dept thread about converting to manual somewhere in this forum. You can probably find it easily through the search function