Help with the factory anti thef system

My factory anti thef system is on my truck and won't go off. I have two keys but not a key fog. Never had one. Bought this truck used 4 years ago. Usually I can put the key in the driver door and turn it counter clock wise twice and it turns off or or key in the ignition. Needless to say truck won't start. Had a mobile mechanic over at my house and he couldn't figure our why and how to fix it. When you turn the key on in the ignition, the security light comes on and it won't allow the truck to start. I've tried locking and unlocking the passenger door locks, changing batteries. Was told if I had a bad cell in my battery it would cause this to happen. Checked all fuses. I'm at a loss. Any help is appreciated.