Systems and methods for operating a circuit. The methods comprise: using a first thermal responsive device to connect a first power source between first and second terminals to which an external load can be connected to the circuit; using a second thermal responsive device to cause a thermal unresponsive device to be in an open circuit condition; and performing operations responsive to a temperature of a surrounding environment exceeding a given temperature value. The operations include: disconnecting the first power source from at least the first terminal by transitioning the first thermal responsive device from a closed state to an open state; and connecting a second power source between the first and second terminals by transitioning the thermal unresponsive device from the open circuit condition to a closed circuit condition using the second thermal responsive device.