Will not start

I recently bought this car. I am in California. I drove the car twice to Bakersfield I drove the car into Lancaster everything was fine then my rear main seal went out and the radiator went out with it, so I got that replaced and fixed and I got the front crankshaft seal fixed as well. I picked my car up from the mechanic shop in all of a sudden now it will not start. It will crank up and turn but it will not catch and start. They are telling me that my key was damaged. So I went to a key place they said unless I hit this key with a hammer is not damaged. So they are saying that it is something with my security system in my car. I have never had this problem with this car, I have had this car for over ten years and never had any starting problems not even close to it, because when I find something wrong with it I baby it and fix it fast. I do not leave in time just to sit around and be able to just be broken down I am trying to figure out could have did something wrong. I turn the key over my security light holds red so I do not know if the security system is locked or what. Please help! There was nothing wrong with this car before I put it in the shop.