Brother DCP-L2640DW shows a maintenance box, drum, fuser, waste toner or service message

The checks in more detail

It uses a separate toner cartridge and a separate drum unit, and each has its own message and its own reset, which is the source of most confusion. Read the message first. A toner message means that the toner cartridge is low or empty, and prints will fade; a drum message means that the drum unit is near the end of its life, and prints may show streaks or spots. They are separate parts that wear at different rates, and a toner message does not mean the drum is worn.

For a toner low message you can often print for a while longer by taking out the toner cartridge, rocking it gently from side to side to redistribute the powder and putting it back. For Replace Toner, fit a new cartridge matching the model; remove the tape and the orange protective cover, and push it fully home. After replacing the drum unit, the drum counter must be reset, or the message will stay on. Open the printer's menu, find Machine Information or Parts Life, choose Drum and select Reset, following the prompts on the display; Brother's guide for the model shows the exact path.

Do not reset the counter without replacing the drum, because the counter is how the printer knows when to warn. If you replaced the toner and the message stays, check that the cartridge is a compatible one and fully seated and that its chip contacts are clean; some third-party cartridges trigger a message. If the message says Replace Toner after a fresh cartridge, remove it, wipe the contacts and refit it, then close the cover fully, since an open cover also shows an error. Print a test page afterwards. Contact Brother with the model and serial number if a message persists.