Engine wont crank

30 Minute Re-Learn Procedure
1. Turn ON the ignition, with the engine OFF.
2. Attempt to start the engine, then release the key to ON (vehicle will not start).
3. Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
4. Turn OFF the ignition, and wait 5 seconds.
5. Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes ( the vehicle is now ready to relearn the Passlockâ Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK).
Important
The vehicle learns the Passlockâ Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
6. Start the engine (the vehicle has now learned the Passlockâ Sensor Data Code and/or password).
7. With a scan tool, clear any DTCs if desired (history DTCs will self clear after 100 ignition cycles).

If this doesn't work check this guide out

https://www.2carpros.com/articles/starter-not-working-repair

Sounds more like a fuel pressure problem. First, PLEASE dont remove the neg cable while the car is running anymore. The computers really dont like it, and your car has alot more computers than the average vehicle. If you remove the engine cover you will see a round vacuum pot mounted on the fuel rail, with a vacuum line to the intake up by the throttle body. Look for fuel in that vacuum line, if there is any at all, the fuel pressure regulator is blown and bleeding off all of the fuel pressure overnight. When you go to start it cold next time, turn key on but dont crank it over, then turn key off, then on, then off, then try to start it. This will build up fuel pressure and it should start fairly quick

Sounds like an issue with the anti-theft system. If you have another key, try it before anything else. Sometimes also the metal shavings will build up in the tumbler, which affects the chip being read. You can try using computer cleaner (canned air) to spray into the tumbler to see if it will help it read. If not you may need to find a GM dealer (doesnt need to be Caddy) to do a diagnostic on the system

Hi:
It sounds like there is a problem with the security system. The only problem is the only way to identify the problem is by taking it to a dealer where they have the proper test equipment.

Either your battery is bad or it needs charged, or lose or corroded battery cables

https://www.2carpros.com/articles/car-cranks-but-wont-start

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if okay-check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs,coil's resistances,cap and rotor,distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems

with compression and valves opening and closing at the wrong time/broken or jumped timing

belt/chain.

Check fuses shown in picture one is under hood and other in trunk. Then make sure you have correct key or try another one if you have one not a new key.

Yes, one is in trunk and other is by battery it is a fifty amp fuse on left hand side under hood. The fifty amp may be a small fuse block.

Will it not take a jump start either? If it goes blank after crank, look for a poor connection. If you have been at the battery connections, and you have physically tightened them, then I would move further down the line. When you try and start, and it goes blank, tug on the positive cable at the starter, and also the ground cable near the starter to see if you regain power. Have you had the battery tested, specifically load?

Sounds like a bad starter. Hold the key in crank possition and bang on starter to check goodluck