Make sure you press and hold the Wi-Fi button for at least 2 seconds.
If the LED light still does not flash, check the following:

• Have you finished setting up your Brother machine?
  Make sure you have completed all setup steps, including the ink system preparation or ink cartridge installation, and printed the Print Quality Check Sheet, as instructed in the Quick Setup Guide.
   
• Is the Jam Clear Cover closed?
  Close the Jam Clear Cover on the back of your machine, and then press the COLOR COPY button.
   
• Is there paper in the paper tray?
  Load paper in the paper tray, and then press the COLOR COPY button.

If the problem continues, check whether any other LED lights indicate an error.

 > Click here to see "Error and Maintenance LED Indications".