[fiily]

Understood, the only thing I can tell you is my experience. If your wiring harness has a break in it somewhere causing the ! , seatbelt, and airbag to come on, it could be quite a while until you can trace everything.

Did the battery die before this happened, were you working on the car, did the 3 lights come on randomly before this, or just a sudden illuminate of all 3 one day?

I would consider bringing it to a porsche shop if you don't want to deal with the hassle, pay the $90-110/hr for diags and fix it yourself after. My gut still tells me it's the airbag reset that will fix it, since all 3 came on. If it was just your seatbelt light, then I would say look at your seatbelt buckle/harness, and replace it, but if all 3 came on all together one day, my money is still on the Clarks Garge reset as plenty of people have run into this issue.

If you do a quick search here on pelican or rennlist, one person couldn't get the lights off after 10-20x's of doing the airbag reset, so he brought it to the porsche dealer and they did what Clark's said to do and it fixed it without any other diags.