Called a dealer in Germany who told me that the receiver would be in the trunk, next to the battery below the spare wheel.
Disconnected this T70 type receiver, waited for 20 seconds, reconnected the module and immediately pressed the OFF button for 5 seconds.
This procedure is described in the X5 user manual in case you add another remote control.
Now the remote works fine!
The manual was talking about the "Standheizung" fuse in the trunk but I could only find this fuse in the glove compartment.
After the "repair" I removed all the circuit breaker from the fusebox in the cargo area while checking the power supply to the T70 receiver and sure enough, the last but one was the one they referred to in the manual as being the Standheizung fuse.
It was called Fernbedienung (remote control).....
The one in the glove compartment is probably just for the auxiliary heater itself.
Thanks again!