I believe this model is a laser printer, and when my Samsung did this, it was a case of shaking the cartridge a little.
But you say a new cartridge/toner as just been installed, then it could well be something more serious. I would suggest that you contact Brother for advice, especially if its still under warranty. If its a 'compatible' toner, then contact the supplier.
Regarding updating firmware, then there is no real harm in trying this out.