The CO2Buddy cannot be calibrated when in alarm.
However if the CO2Buddy hasn't been calibrated in a while it can drift the readings to alarm levels. The fix below only works if you have alarm configuration 1,3 or 4.
If you first change the configuration of your unit to configuration 2, (AC2) following the steps below.
Once the configuration is changed, unplug the system from the charger. And calibrate following the steps below:
Then once this has been completed return the alarm configuration back to its original setting.