Water in cabin. now getting Immobilizer DTC
 

Hey guys.
As the title suggests, I recently had a large amount of water enter my cabin.
I drained the water, and was able to start and drive the car, however a few days later, my steering lock would not unlock.
I was initially getting DTC B2782 error code (which relates to the steering lock ecu, technically a "power management malfunction" which technically is the SMT assy), however that seemed to fix itself after a few days.
However, I have a persistent immobilizer communication error. DTC B1572. The car wont unlock the steering wheel and won't crank, but apart from that seems to be functioning normally in regards to the green key icon, doors unlock correctly etc.
I've thoroughly checked all connectors in the car, cleaned them with lanox, and have tested for low resistance to ground on the immobilizer pinouts on both the ECM, and SMT ECU.
Both connections seem fine, with less than an ohm on each end, and 50k ohms to ground, which pretty much leaves me stumped.
According to the wiring diagram (pages 111 and 119), there is only one IMO connection between the ECM and the SMT assy (certification ecu) am I correct in assuming that this must mean I have an issue with the SMT or the ECM itself?
Is there any other connections I should check?
I have already removed the SMT and inspected it, and it looks fine. the board itself is completely potted, so I doubt it could be a problem, but I am running out of ideas.
I know this is a fairly complex topic, however this is my last ditch effort before surrendering to the mercy of my dealer and sacrificing many hundreds/thousands of dollars in labor for them to tell me the SMT is dead.

salt or fresh water?

Fresh.
Rainwater.

Time to start disassembling everything inside and checking electrical connections. Disconnect all, clean if needed. Spray them down with electrical contact cleaner and possibly coat the bad ones with DC4 electrical insulating compound.

Did you figure this out yet? im having same problem.

its the ac drain