no sound from my radio, disc, nav, phone,etc. They all seem to operate OK.

This is a seemingly common issue with Porsche vehicles with the fiber optic output on the radio. There is one thing you can try, pull the radio fuse for a few minutes and put it back in, or, try locking and unlocking the doors a few times from the exterior of the car. If that does not solve the issue, either the battery is staying in power savings mode, or the fiberoptic cable may be damaged.