No start problem

I have a 2007 cobalt 2.2 liter that won't start or try to start.
We've replaced the starter checked all fuses and relays .
the battery is good and charged. I get dash lights but they
turn off once key is all the way forward. No lights outside
the car and radio doesn't come on now. Also check engine
light was on prior to the car dying and not starting again
and now it doesn't come on at all. Finally the auto theft light
flashes on briefly with the other dash lights momentarily
and then shut off once key is fully forward.