security light on cluster, wont turn over?
 

So i bought a 2008' ford fusion. Owner said they had to replace the battery and starter because it was having starting issues. I paid for the car and tried to drive it home, after about 10
minutes it finally started. Having to twist and turn the key at different angles, sometimes it would start and you could hear the starter motor go, but was not hitting all the ignition spots.
every time i push the shift lever with the key on it makes a click in the steering column if that means anything. I called the dealer and they wanted $688 alone for the whole ignition, and 3 hours labor. I did not want to put that much money in it since i already just bought the car. I ordered a matching whole ignition off of ebay that came with the key. Car was still starting before i pulled out old ignition. Only difference between new and old ignition is the old one seems to have a bare piece of metal(magnet) right in the center bottom where it mates with the steering column, new one has a piece of black plastic where the old one doesn't? I installed new ignition(removed key cylinder from new ignition and placed my stock key cylinder in its place), and it wont start at all.security light just flashes no fan,lights,blinkers. I switched out the ignition switch & nothing, also switched out the black ring that surrounds the key that plugs into the harness.Also my key fob stopped working after i pulled old ignition. I read online that you can put your key in the driver door and turn and hold for 30 seconds, but i tried that and nothing! I am really at a loss and would Love for someone to give me an idea of what i am doing wrong. Grounds in engine compartment are clean and tight & battery is fully charged & tight. Flashing security light is killing me, newest car i have ever owned and don't know anything about it honestly. Any comments or tips would help out. Thanks for looking.

You're not gonna like this.
As you already know by now the security system does disable the starter from operating when conditions are not met.

The security system in your vehicle has to recognize a special coded key before it will start. If there is anything wrong with the key , it will not start.
The coded key has to be programmed to the computer in your vehicle . This can be done by a certified locksmith with access to security info for your vehicle
Once you attempted a different key system, which I believe you did, now the computer is confused and will not respond even if you put everything back to the way it was.

You do have 2 choices however.
Dealership- they have access to "as built" info to reprogram everything once they get everything in working condition.
Certified Locksmith - they will also come to your home, most will, they can reprogram keys and the vehicle computer and they usually charge less than a dealership.
All this is dependent on coding and reprogramming . . I do not think either will do any repair work at your home. and both may require the vehicle be towed to their location.

What started out as a 688 dollar problem can now be considerably more.
Suggest you check with a couple of locksmiths and get some idea of what they can do and what they might charge. You might wind up having a dealership correct it.

Suggest you check around and get some other opinions.