I see that other users have also run into this issue when using Pycharm, but coundn't find a fix when error with import open3d. I have tried the approaches suggested however, adding to Path did not work (Windows 10). Many thanks for your help!
Found a solution! The issue was multiple versions of Python installed. I deleted Anaconda and any other Python versions. Then reinstalled a 'fresh' version. This solution is further explained here:
How to resolve "ImportError: DLL load failed:" on Python? How to resolve "ImportError: DLL load failed:" on Python?