We have already booked a flight from Hamburg to Shenzhen ( in 22.12.17,departure 04.01.18).

We would like to use the 144h free visa there, as we fly to Malaysia from 24.12.17 to 03.01.18. (I would point out that we do not want to leave the Transitzone at the transfer point of the flight in Beijing, so we need to be qualified for this.)
Now we would like to visit Hong Kong in the days from 22.12.17 to 24.12.17.
Can one go with the 144h-free Visa in the direction of Hongkong and also again to the city?