It sounds like you may have a problem with the immobilizer/central locking system. There is an electronic module mounted on the floor under the driver's seat. They get wet and corrode internally.
Check for moisture in the carpet padding under the seat. If that is your issue, there's plenty here on the forum that can discuss it.
Type this into a search: site:986forum.com wet immobilizer
and look thru the results.
If you need to get the top open, here's a video, but I wouldn't do all that before checking the immobilizer for moisture first:
https://youtu.be/QOLhAR8bLio