[Tristar Ltd]

I kindly request for kind assistance or advise, 
I am working on a G-Wagon G55 M113k whose ECU and SAM module were exposed to rainwater. Initially, the car wouldn't start, and the fan ran at high speed. I removed, cleaned, and reinstalled the ECU and SAM, but the car still wouldn't start. Reprogramming the ECU allowed the car to start, but during a test drive, it shut off after 30 minutes and I wouldn't restart it, until after 3-4 minutes. I managed to drive it back to the workshop and I repeated the ECU reprogramming, suspecting it was the issue. While the car can run for 1-3 hours, it consistently shuts down after being parked or fails to start after turned off. Any insights or suggestions would be greatly appreciated, as I may have overlooked something.