No crank no start

So my mother has a 14 Chrysler 200 6 cylinder. The key
stopped working to lock or unlock,  and now the car will
not start.  Tried putting a diff battery in the key tried
jumping the battery,  looked at starter, and still will not
start.  No crank no start. So the security light is on in dash
and all the lights work. I don't know if it could be a security
thing with the key with the security module or something
that needs to go to a dealer or if it's something that we
can fix.  I did take it to Firestone (only because it was a
block away from where it wouldn't start)  they told me it's
throwing out a bunch of security codes and it needs to go
to a dealer since they can't figure it out exactly.  Any advice
or any one se this before?