What do the LED indications mean?

I just replaced the toner cartridge and the LCD continues to display the message "Toner Low" / "Replace Toner" / "Toner Life End" or the Toner LED is still on or flashing.

The Drum LED is still on or flashing after I replace the drum unit with a new one.

I don't think I got the full yield from my high-yield toner cartridge but the message "Toner Life End" or "Replace Toner" is displayed on the machine or the LED is on or flashing.

There is no jammed paper in the machine, but still the Paper LED is ON or Flashing.