How do I convert the following files into one executable? 

A main.py file that imports five other python scripts
Five python scripts that each have their own GUI
A background image is used in the main.py file

I am using Python 3.5.2. I have tried py2exe, cx_Freeze and pyinstaller but none seem to work, or I am doing something very wrong. Please could you help with clear steps.  
It seems I have to downgrade to Python 3.4 in order to convert successfully but I don't really want to downgrade.
I am using tkinter for GUI and the Python math module for rounding-off numbers.
I've had some success with pyinstaller and a program using enaml (Qt backend) for the GUI. 
For pyinstaller it helps to use the --debug option or make a .spec file and set debug=True. Also, pyinstaller has the option to make a single folder with an exe in the folder instead of a single exe, this might be easier to debug. You can distribute your single-folder programme by making a single-exe installer with software like InnoSetup.
How to covert multiple Python 3.5.2 scripts and an image into one executable?