My car was vandalized and my car stereo was.

My car was vandalized and my car stereo was ripped out and ever since when I go to start my car I get a security light flashing and I have to put my key in the on position and wait about 10 minutes for the security light to stop flashing. When I took my car to the insurance company to fix the window I told them about the problem they said they would check it. When I received the car back they said there were no problems with the security system but this problem still exists. What could be causing this problem