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Transmission failsafe scheme.


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Hello. My 2001 E53 X5 is experiencing gearbox failsafe mode. The gearbox was replaced by an expert in my area 2 1/2 years ago. Everything was functioning well until around a month ago, when sometimes the gearbox failed to move up to 3rd gear. Switching to manual mode enabled full control over gear shifts in both directions. Restarting the automobile after stopping it should be sufficient for a few days to a week. Otherwise, everything is OK.
Today, I took the vehicle back to the expert for diagnostic testing. However, after travelling about one mile, the gauges on the instrument cluster stopped functioning. Speedometer not working. Lacks a tachometer. The temperature gauge needle was in the heated zone. Everything else functions well, including windows and automatic adjustment for steering wheel and seats with the comfort option.
When the diagnostic tool was connected, it displayed just 3 modules instead of the expected larger number, suggesting a potential CAN BUS issue as indicated by the mechanic.
He proposed that there may be a defect in the wiring or body control module.
Can anybody provide insight based on experience with this or a comparable issue?
Could a faulty fuse be the cause? Possibly a faulty plug connection?
Thank you

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Inspect for water infiltration at the DME/ECU since the temperature gauge rising directly to the red zone suggests a lack of communication from the ECU.

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The area surrounding the engine control unit beneath the cowling is quite dry. Tomorrow, I will make sure to move the object away from the wall so that I can open the passenger door and access the glove box. I will also inspect all the fuses in that area.

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Update. I performed a diagnostic on the vehicle when it was cold before to starting it. The ignition was the only component that was activated.
At this moment, DD can timeout. ASC/DSC DC CAN timeout, electronic transmission control (EGS/AGS)
Signal 78 monitors vehicle speed, whereas signal 80 is used for CAN BUS monitoring.
82 Canadian dollars ABS/DSC signal 81 had a Controller Area Network (CAN) timeout. DME
Front right wheel speed sensor is not transmitting any indications.
Front left wheel speed sensor at position 21 is not transmitting any signals.
Internal malfunction of the 68 steering angle sensor.

Some of those occurrences may be attributed to the fact that the automobile remained stationary, but I am uncertain.
I drove it for 30 minutes and it performed well.
The heater blower motor was not functioning, and the hill descent switch was lit and could not be deactivated.
There are no warning lights illuminated on the dashboard.
While driving, I attempted to reconnect my scanner, but it failed to establish communication with the automobile.
Arrived home and turned off. Upon restarting, the vehicle entered trans failsafe mode, displaying no speedometer or rev counter, and the temperature gauge indicated a high temperature in the red zone.
I am unable to comprehend the current situation.
Does anybody worldwide have any ideas?
I need a specialist located in close proximity to Cambridge, UK. Anyone...

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