You have to turn High voltage ON, and check the voltage and the current are normal. When the alarm of HV rings, check the HV monitor and turn ON the channel which is Off. You have to monitor the hit pattern and check if there is a counter with low statistics. You have to monitor gains of ADC by the histograms and call expert if you find a low gain. You have to monitor the peak position of on-time events of TDC by the histograms and call expert if you find an non-negligible shift.