I have an 07 infiniti qx56 ...never had any problems before...i changed the battery and it threw it into Anti theft mode...please tell me how to get passed this ...because my car won't crank

Use your OBD code reader.

https://www.clubarmada.com/threads/erratic-tachometer.17405/
This thread has several suggestions from a failing battery to bad grounds or BCM problems.

Anti theft warning light.

I HAVE A 2005 INFINITI QX56, my cruise has stopped working, does anyone know what the cruise box looks like and where its located? I cant get any dealership to tell me or show me. Thanks

check the starter and celonid

you take a12v test light connect it to grond on chasey touch each side of fuse if fuse is good light will come on if not fuse is blown.

This is from Ken on CarPros:
Here is the way to reset the security system.

https://www.2carpros.com/articles/how-to-reset-a-security-system

Here is the systems descriptions

There are 2 security system, namely anti-theft and immobilizer.

Here are the 2 systems.

DESCRIPTION & OPERATION
Anti-theft system is controlled by Body Control Module (BCM). BCM receives signals from hood switch, trunk switch, door switches and Local Control Modules (LCMs). There are 5 LCMs located throughout vehicle.

To set anti-theft system in armed mode, remove ignition key, close all doors, trunk and hood. Lock doors using key or remote controller. The SECURITY light will illuminate for 30 seconds, then flash in 2.4 second intervals, indicating system is in armed mode.

To cancel armed mode, unlock and open any door or trunk lid using key or remote controller. SECURITY light will flash every second, indicating system is disarmed.

Alarm will activate (horn sounds, headlights flash and starter circuit is disabled) if any of the following conditions occur while system is in armed mode:

Engine hood or trunk lid is opened using the hood or trunk lid release.
Door(s) is unlocked without key or remote controller.
Tampering with any door/trunk lid key cylinders.
To deactivate anti-theft system, unlock door or trunk using key or remote controller.

If it is the immobilizer that is preventing the engine from being started, ensure you have the correct key and the transponder is intact. Quite often keys are dropped and if it breaks open, the internals would scatter all over. When this occurs, there is a tendency for the transponder to be lost.

Please let us know happens so it will help others.

Best, Ken
I hope that helps you out!

There is a motor for one of your Air Conditioner mode doors is going bad, resolve quickly!

I have been able to reset the check engine light by disconnecting the positive battery terminal for 15 to 20 minutes. This will cause to system to reset and the light should go out. The system will automatically go through a diagnostic cycle to check for problems.

It sounds as if you are having a battery problem. You need to have the battery checked at an Infinity Dealer. The battery should have warranty on it (pro rated) with such a new vehicle. Hope this helps.