Security system reset?

Car wont start. Replaced ignition switch. Believe its the passkey 3 system in anti theft mode. But doors are still unlocked and accessory power works sometimes but wont completely turn off unless I disconnect battery. I am 3rd owner. Have no key fob and chip is not in key but in ignition lock cylinder I guess. Need to bypass or fix so car will start. Checked fuel and starter etc. Arced starter it ran for 3 seconds then shut off. Tested battery etc. Help please.