First off, thanks for reading, and I look forward to any and all advice.

2016 RRS with TD6. I purchased the car from an auction. The car was marked "flood" but flood was loosely used. Upon inspection this is what I found. Car was originally in California, then in Kansas. Underside of car shows no signs of anything rusting, or corrosion.

Windshield was cracked, and what looks like a drilled 3" hole was somewhat repaired.
Rear hatch showed no signs of water damage, in the spare tire area, battery area, or inside the wheel well where the electronics are.
Pulled the US drivers side trim and found the trough was full of standing water.
Pulled the seat, and the carpet found the amplifier completely rusted out potentially beyond repair.
Checked the wires found no visible signs of damage, or corrosion. Did find what looks to be 2 factory splices, but those look to be with adhesive lined shrink tubing. I have not opened those up yet for further testing.
Checked grounds at foot well no corrosion.
Pull the trim on roof since I read that roof drains are a likely culprit. This vehicle has a panoramic roof so that was a dead end. No drains.
Checked all the fuses, have not checked relays yet since relay tester is still in route.
Pulled starter, tested fine.
Checked junction at passenger wheel well, it was clean, pulled apart and wire wheeled it anyway and put back together.
Checked earth grounds on engine, and at battery. No issues.
Upon going down a rabbit hole of thinking it was out, or low on DEF I did find that the DEF filler nozzle was completely broken off. But my scanner was able to test how much DEF was in the tank. Its slightly low, but I don't think it was low enough to cause a no crank, no start condition.
Checked codes with Autel MK808 and found only codes referring to DPF. Did find that no starts were available due to DPF so I reset that. Still no crank, no start. Battery was completely dead upon delivery so its possible whatever codes were stored are now gone.

Currently believe water is entering through windshield repair. This repair is near center bottom of windshield.
Next step checking modules inside center console.

Question- what modules are against firewall inside of car that could potentially cause this no crank, no start? Passenger side is dry so water is concentrated to the drivers side.

 

Modules that will prevent the car from cranking are Instrument Cluster Module, Body Control Module (Located under the drive dash), and PCM. (at least IMMO wise)