Pull out the connector of the flex cable vertically while supporting the circuit board (I used a plastic spudger to push down the circuit while pulling the white connector). To insert it back, simply push it back into the slot. Note the orientation of the connector (Take lots of pictures)

Note the black plastic pillar - the white focusing gear (obstructed in this shot) from the focusing ring needs to go back inside this during re-assembly. It's a little tricky.