If the unit has not fully cooled down then the temperature may reach the limit soon after the amplifier is powered up.
Over temperature is caused by a combination of high listening levels and low impedance speakers. The Edge W includes temperature detection which constantly monitors the heat generated by the output transistors.
If the monitored temperature reaches a high level (suitably within the limits of the output devices) the amplifier will automatically switch into a fault mode To protect itself from damage.
If the loudspeaker impedance is low the temperature of the amplifier may rise faster as the amplifier is working harder. If the amplifier is mounted in a cabinet or the ventilation slots are obstructed the over temperature detection may activate/reactivate after a short listening time.