What should be done when the BATT 1 OVERTEMP message appears on the EICAS?

When the BATT 1 OVERTEMP message appears on the EICAS, turning off the associated battery switch is the appropriate action because this message indicates that the battery is overheating. Allowing the battery to continue functioning in this state can pose serious safety risks, including the possibility of battery failure or even thermal runaway, which may lead to a fire. By turning off the battery switch, you effectively remove the source of the overheating, allowing the battery to cool down and preventing any further complications.

This action is crucial for ensuring the safety of the aircraft and its systems. It is important to monitor the situation closely and prepare for any further procedures as necessary, typically in consultation with maintenance personnel or following emergency procedures.