Land Rover Repair: 1998 RR hse will not comunnicate with nys dmv, hevac, becm

Question
The sunroof had been left open during a hurricaine. I dried the Range rover out with a heater for almost a week and the Range Rover got me through the winter untill the warmest day last March. I had used a string for the fuel flap but made a switch instead on fuse lid. I may have burnt something then. I swapped out four times to California for becm and ecu. I finally found door switch was burnt,problem fixed and Range Rover started but would not communicate with a garage computor. I bought a becm set,key barrel with a coil this time and door handle(not changed yet) and fob from UK. Range Rover would not start so I sent for the RF and change that, and the Range Rover started. I went for inspection and the darn thing won't communicate. Also through all this my hevac illumination will not light nor the right side of hevac. I have tried three units and no good. Plus my temp gage will not rise above vehicle start.
Can you help me and where do I start I mean if it something so simple as a door station....I can do that but I have over $20,000 in this calif. rover plus trucking fees,new engine and heads I am in dire straights...thank you John
PS if need be I can somehow get it to your shop

Answer
You might have a failure in the BECM, but more likely you have a fault in the wire harnesses that run to and from the BECM and along the passenger floor.  We fixed two similar complaints this year; both turned out to be wiring corrosion.  That's likely in your case as you say you had water inside.    Hopefully you did not get water into the BECM.  If the wiring was not taken apart and cleaned promptly you probably have considerable corrosion and this may be just the tip of the iceberg.  

Take a look at it but you may need to bring the truck up here and take the train back to NYC till its sorted out.