Sometimes your printer continues displaying the low toner message even when you have completed the process of Brother printer replace toner. In this case you have to reset the toner counter to fix the error. The process differs a little depending upon the model but here are some basis instructions. Open the cover of the printer and press clear. You will now see replace drum message. Now, click on start button. With the help of up and down arrows, move to 00 display. Now, click on ok. Cover the lid back. This should resolve the low ink error.
https://connectmyprinter.com/how-to-change-toner-in-brother-printer/