Multiple electrical issues, either IPDM, ECU, BCM, or something completely fried.

I ran some errands this morning, truck started and ran fine through the errands until the last stop. I arrived, idled for about 20 minutes, turned the truck off, spent about 20 minutes inside. Came back out, truck started fine- Noticed that the AC was blowing hot, but it was warm outside, so I didn't think anything of it at the time. Backed out of the parking spot(Idle speed, no throttle applied), and pulled up to the exit of the parking lot the same way. I noticed that when I attempted to enter traffic that my accelerator pedal had no response, and I noticed the SES light on. AC compressor light still on, still blowing hot air. I made it to another parking lot safely. Turned the truck off, restarted, tapped the accelerator pedal, and no response. Turned truck back off. I decided that I'd try to reset ECU. Pulled the negative battery cable, left it off for about 15 seconds, hooked it back up. Attempted to restart truck, and wouldn't start(It would and still does crank/turn over). No SES light, though. Now, cooling fan runs while the truck ignition is on(but not started), it's NEVER done that before. Borrowed OBDII scan tool from parts house, and it would not establish a link. Purchased new ECU relay for IPDM, swapped and replaced, no dice. Cooling fan still runs, tried a different OBDII scan tool, still no link. The connector has power, as it turned each OBDII scan tool on immediately when I plugged them in. I also noticed that the backlight on the odometer randomly dims and brightens.

Test lighted every fuse I could find, IPDM, the other little box in the engine compartment, and all of the fuses on the passenger side in the cabin. None blown.

Double checked battery connections, everything is tight and clean(No corrosion)

I'm out of ideas as far as troubleshooting. Next steps are to start replacing IPDM, ECU, and BCM.

Any suggestions?:frown:

2007 Titan LE, 145k-ish miles
No security features(No chipped key or other passive anti theft systems)