For Brother DCP/MFC Series printers:
1. Open the front toner compartment door.
2. The printer screen should read “front cover is open”
3. Press the “clear” button on the printer’s front panel.
4. Printer will say “Replace Drum?”
5. Here do not press 1 but instead type in “*00″ on the keypad.
6. The screen will say “Accepted”. Close the door
For Brother HL Series printers:
1. Open front door
2. Turn off printer
3. While holding down the GO button, turn printer back on
4. When all four LEDs light up release GO button. All LEDs will turn off
5. Press the GO button 2 times. The 3 LEDs will light up solid
6. Press the GO button 5 times
7. Paper light will be blinking
8. At this point the toner end-of-life condition has been reset.
Here is a little tips for you: timing is important here so don’t pause between button presses. Besides, you should pay attention that different printers and toners need different steps to reset. The above method is suitable for the printer of Brother DCP/MFC/HL Series which should work with toner TN-720, TN-750 and TN-780.