DIAGNOSIS No. This model does not have a backup battery for the clock. The control board relies on constant mains power to retain memory.
FIX This is normal operation for this design. After a power outage or disconnection, the display will show 0:00. You must manually reset the clock each time. Press the Clock button, enter the time using the number pad, then press Clock again to set.
IF THAT DIDN'T WORK If the clock resets without a noticeable power interruption, the issue is a failing component on the control board's power supply section. The clock circuit is losing voltage.
HEADS UP The cooking programs and custom settings are also lost when power is cut. There is no way to add a battery backup to this model.