I have a 2005 Porsche Cayenne S and for 3 weeks now it won't start.New battery installed...

It started when I put the car in park to open my
complex gate...and when I put it in drive...it just
shut off and started reversing instead.So I
restarted it but it still went in reverse instead of
moving forward. I got scared and put it in Park and
waited. To get it off the street I put it in Nuetral and
had it pushed into a vacant parking spot. It has not
started since. The key is stuck in the ignition and
when I try to start it...it says to move selector to
position "P" or "N".
I would also like to add that I did drive this car from
Houston,TX to Sacramento California with no
issues. Had it checked out before taking it long
distance. The day is stopped it was 112 degrees
outside.