Bluetooth Pairing has scrambled the Computer

[Grommit]

Hi there,
I got a new phone (Samsung S9+) last week so decided to pair it with the car (E53 2005), as I have done with previous 2 phones.
It took a few attempts, as usual, but eventually got the code request and paired it.
However after pairing, the radio started switching on  and off randomly, none of the buttons on the headunit seem to work properly, although the dials do still appear to function.
Have tried "Unpairing" them, using the original phone, disconnecting etc, but problem persists. The whole system seems to have scrambled and I am unable to do anything other than listen to the last radio station. Even the Menu button has no effect. Anybody have an idea for a solution?
I assume the problem lies in the new Bluetooth protocol being incompatible with older system in the car, so it will likely never work,  I now just want to reset the system so it is usable again.
Any advice appreciated.

[Alan Gunn]

Disconnect the battery for 30 minutes that will give it time to reset everything.

[Grommit]

Tried that, no joy!