The Ez3D software only works with Ez3D firmware.  Installing any other firmware will prevent the software from ever discovering your printer.  If you re-flash your firmware, and want to revert back to Ez3D's firmware, follow these instructions:

  1. If you don't already have it, download the Arduino software.
  2. Download the Phoenix version of the Marlin firmware.
  3. Extract the ZIP file.
  4. Rename the PhoenixMarlin folder to Marlin
  5. Open the Arduino Software.
  6. Open the Marlin.ino file from the Arduino software.
  7. Click Tools->Serial Port, and select the serial port your printer is on.
  8. Click Tools -> Board -> Arduino Mega 2560.
  9. Click the "Upload" button.