Cannot turn off security

You can get it out of theft mode also by using the key to unlock a front door. If that doesn't work, check for broken wires between the door hinges.

I have tried that it doesn't work.

Did you find any broken or frayed wires? Two of them at each front door are for the "arm / disarm" switch attached to the lock cylinder. On most of the Jeep models, that wiring harness can be unbolted and unplugged, so it can be repaired at the comfort of the workbench.

Broken wires usually occur at the driver's door first because it gets opened and closed more often. You should still be able to turn the system off by unlocking the passenger's door.

We tried unlocking the passenger door. Is there something special we need to do when we unlock it? No frayed or broken wires.

If the wiring is okay, that leaves the switches inside the door. A linkage to the switch may have popped off, or the switches could be defective. The easiest and fastest way to diagnose this requires a scanner. Under the "Inputs / Output" menu it will show the ""arm" or "disarm" state the switch is switched to with the key. What you're looking for is one that doesn't change as you're cycling the lock back and forth.

I should mention too that along with wires that fray between the door hinges, the insulation can crack off and develop bare spots. While not real common, if the right two wires were to touch, it could make it look like the lock cylinder is constantly in the "lock / arm" position. I doubt this has happened in your vehicle because if this started right after the battery was disconnected, and no memory saver device was connected, that does put the system into theft mode, but without the horn blowing. Bare and touching wires would have caused a problem before now. It is much more likely this is caused by a switch or broken wire.