Haven't had it on the 159 but did have it many times on the 147.
What I'm told happens is that the controller "forgets" the position on the
roof and goes into shutdown/failsafe.
You should be able to reset it by turning the switch to fully open,
pressing it in for 10 sec and then fully closed and press for 10 sec.
Continue until it sorts itself out.
If it still doesn't free-up try turning the button to each position
and pressing it in turn. Bit hit-and-miss but playing around with
the 147 one used to free it up without resorting to a dealer visit
for an Examiner reset.
I was told with the 147 never to leave the roof in any position
other than fully open, fully closed or fully tilted to avoid this
There is a manual winder which is just a hex-socket on the motor
which you turn with an allen key or supplied winder.
Welcome to AO BTW.