Rear wiper washer - does not stop sparing liquid

[Kisu_san]

I had a strange issue yesterday. I opened boot and placed a pram and close the door. Then rear wiper washer jet started spraying the washer liquid.
It did not stop until the washed liquid tank drained completely

I tried pressing and releasing the washer jet button below the steering, stopping the car etc, but no use. After washer liquid was drained, I could still hear the motor was spinning.

Finally I removed fuse 81 from boot, that stopped this motor. I filled liquid and I use to wash front windscreen.

Does anyone has experience fixing rear washer jet?

Any ideas what might have went wrong?

Thanks in advance
Kishore
-----------

BMW X5, E53 2002 3.0i Euro model
152K kms done so far

Recently changed break pads, break oil and rear wiper.