Try deleting your preferences. On MacOS they'll be in your Library directory under Preferences/Autodesk/maya/2017/prefs.
Apple has unhelpfully decided that you shouldn't be able to see your Library directory in the Finder. To get around this, go to your Home directory in Finder, then use the Go->Go To Folder menu item and tell it to go to 'Library' (without the quotes).
If deleting preferences doesn't work, try to get an error message by running Maya 2017 from the command line. To do that, open a terminal window and execute the following command:
/Applications/Autodesk/maya2017/Maya.app/Contents/bin/maya
