You might consider talking with this company. They can rehab your unit. ecudoctors.com/pages/porsche
A faulty ignition switch can also cause several issues.
https://www.pelicanparts.com/techarticles/Boxster_Tech/86-ELEC-Ignition_Switch/86-ELEC-Ignition_Switch.htm
Stay with it, don't give up and report back what you find.