Help needed
 

My battery went flat so i Replaced the battery, now I have no dashboard lights and a steering fault Keeps coming up on dash . Nothing happens when I turn the key ? Radio working, Interior lights come on ..

You replaced the battery or auto service place? Auto service place should have known better. A batter tender (minder) is needed. Check with Rennlist Porsche forums, more techies there.

Unfortunately a visit to Porsche dealer might be necessary.

The lesson is that one should always research first to avoid these issues. One suggestion was to use a backup battery connected at the engine terminals to avoid the loss of critical info. You may want to look into Durametrics as they have a cable and software to assist us DIYer's when this sort of thing occurs. It's a bit pricey but worth it if you use it more than a few times...good luck!

My guess is that you have probably sorted this out by now. The steering error is a standard Porsche thing and will disappear when you turn out of the driveway. The non-starting is most likely because the battery was not fully charged. You did not give a lot of detail like the year and model of Cayenne and what type of battery so the response is equally generic. Some Cayennes have 2 batteries so there are a number of different possibilities here. I doubt you have done any damage and my bet is that you have already straightened it all out and are a happy camper.