For the investigation the logfile was analysed.The described problem could be retraced, it was found that the device was run in battery mode and the device shut down due to a used up battery.During the startup phase of the device the battery life state will be checked by the power supply.In case that the battery is not ok any more the power supply will perform an acoustical alarm for 30 seconds, as it was seen in the logfile in this case.After startup of the device the user will see the discharged battery during power on self test and in normal operation on the screen (battery level 0% in right upper corner).In case of a power supply failure, for example because the power plug is pulled, the device continues operation using the internal backup batteries without limitation of functionality.The remaining capacity of the batteries is indicated to the user and additional warnings are given when the residual battery capacity underruns 20% respectively 10%.The batteries are subject to an aging process and are replaced periodically during product maintenance (each 3 years).In this case the device already displayed the status of an ¿old battery¿ several times before the case in question, the battery was relaced and the device performed as specified.The number of similar cases, related to the same root cause, is within the expected range of the respective risk assessment and thus accepted.
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