The Brother machine has separate consumables the toner cartridge and the drum unit. Verify you replace only the drum unit and not the toner cartridge. Keep the machine powered ON. Replace the old drum unit with new one, put it into the printer. The cover let’s stay open. Press power button 4 times. Close the cover. The drum is now reset.
This procedure is also for: DR-1000 DR-1050 DR-1030 DR-1060 DR-1070 DR-1020