I suspect two things for now:

  • you haven’t created a “data” folder. the server will not start in this case. this one is the highest possible reason in my mind.
  • along with the data folder, the default config file might be missing (can’t say why).

try running mongod --logpath ~/mongocrashes.log in the terminal. it should give a better log so we can examine it. use “upload” button in your answer and attach it.