There is a way to reset the ‘replace toner’ message on the newer Brother laser printers.
- Open door to toner cart
- Close door
- Press SECURE and LOCK at the same time
- Up and down arrows to select
- Select the cartridge to reset
Apparently, the cartridge you select to reset just determines how long the printer will wait before the “replace toner” message comes back on. Picking the TN820 HC toner option should work for a while.