The Brother Printer Offline Mac problem can be resolved as shown below. Make sure your printer is powered up and switched on. Make sure the loading tray has enough paper. Look for any paper clogs and remove them. Check to see if your printer is experiencing any new problems. You should be able to connect your Brother printer to a wireless network.
Make sure your computer can identify the printer and that the USB disks are properly placed into the USB ports. Further, eliminate the entire printing queue. Make sure your Brother printer's firmware is current.