A “Re-install missing or unresponsive fuser [31.80]” message usually means someone removed the fuser while the power was still on. This can also occur if someone removed the fuser while the printer was in Sleep mode and, subsequently, the printer wakes up from Sleep mode.
Note: End of life consumables such as fuser, transfer roll, and/or pick tires can cause some errors. Check the fuser's status using the printer's Control Panel. Order a maintenance kit if the fuser is already near its 'end of life' state.