battery is fully flat or disconnected, check for water damage at the battery itself, the fuseblock near it and the grounding points near it too (plastic pull out under seat)

there is junction connector for the CANBUS which will go haywire with water on it/in it (its on the floor of the car)

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)