I think I may be confusing GM and another manufacturer. GM may very well apply B+ rather than ground. Either way we need to see if it'* getting a start signal.
I just seen that diagram and it is B+ from the PCM. I mixed GM up.

is there a way to check that start signal with a multimeter?

No. Do we know for sure that the PCM uses that strategy? What I mean is that the strategy it uses for anti-theft? What does the theft light do?

I’ve actually never seen the theft light come on for this vehicle the whole time I’ve owned it. I also did the anti theft relearn procedure since I installed a new pcm
the procedure was to leave the key on for 10 minutes and then turn the key off for 5 sec and then repeat that two more times then start it but nothing changed.
Do you think I messed up something from reinstalling the pcm and disconnecting the connecters to check for possible wiring issues?
I also know that the Body Control Module along with the theft deterrent relay can decide whether or not to send the fuel enable signal to the PCM. I’ve already checked the connections to the BCM and they look okay but I never actually checked for power and ground.

You may have bricked it. We need a good scan tool. It'* possible you may need to get a BCM as well.

I’m assuming I’d have to get another BCM programmed to my vehicle by the dealer? I know just a pcm update costs almost 200 dollars.

Hopefully you can read this screenshot but this is if it sets that code which it hasn’t but the highlighted information was important.

Yep.Call shops and tell them the story and they will be able to tell you if they can do it and how much it will be.
Probably don't need a dealer.

Okay, I’ll eventually get around to doing that. Thank you very much for helping me narrow down this problem. I’ll make sure to post what I find or what a shop figures out.

Let me back you up a little.
Did you replace the BCM and PCM with new parts or were they in anyway of the term used/refurbished/salvage picked, etc
if not new, you are not going to get your car to start. The VIN number in the used PCM or BCM and/or the part numbers (if not the same pn) being different will just lock you out of starting. This is to prevent theft by swapping modules. A new module or pcm or bcm Etc when put into the car will learn the proper VIN/fuel enable/disable passwords from eachother, but a USED one requires SPS and/or a tech2/MDI/high end tool to adjust Part numbers/VIN number. being 2007, there may be additional or different kind of learning procedures for new modules Im not mentioning that I dont know of. (SPS means reprogram btw, a tech2 may not be able to perform that being it has a CANbus network but if you had the hardware, GM does license out calibrations you could try yourself... but I wouldnt just try it on a whim, you NEED a tool that can read and talk to these modules, period
Otherwise your throwing money away

The PCM will learn the incoming fuel continue password immediately upon receipt of a password message. Once a password message is received, and a password is learned, a learn procedure must be performed to change this password again. A PCM which has been previously installed in another vehicle will have learned the other vehicle'* fuel continue password, and will require a learn procedure after programming to learn the current vehicle'* password.

this is why I asked if you still have your original BCM and PCM, if so, please put them back in. If you do NOT have them, you will need dealer level scan tool and / or programming to override the original cars they came from. If you bought NEW parts(not sure if available anymore even, but its possible?) then you may just need to do a Passkey long relearn but I doubt you got new new modules