traveling in Shenzhen

Just as your arrangement, you only have two days to visit the three places. So a route is suggested as followed:
The first day: Since your hotel is close to Huangbeiling Subway Station of the Shekou Line, you can catch the subway from Huangbeiling Station to reach WOW station. After that, you can walk to Splendid China, which is near WOW. You need to walk to Overseas China Town Subway Station and then you can find the Splendid China. You can spend the whole day on these two places, even including the evening. Then you can take the Shekou Line to go back to your hotel.
The second day: You still need to take the Shekou Line to arrive at Hubei Station, getting out of the station from Exit C and then you can walk talong Shennan East Road to Dongmen.