Expected behaviour when you push calibration switch inside the room is that LiV will start using the actual indoor concentration as a reference for 400ppm. So, if you calibrate the CO2 sensor when the CO2 level is say 800ppm, LiV will show 600ppm when the CO2 level goes to 1000ppm and so on. You just need to calibrate the sensor outdoors to restore normal operation.
If you see the value -999 on the LCD screen, you can check a few things:
1) first make sure you can read the sensor:
Test K30 sensor:
>sudo python co2Sensor.py
2) have a look at the log file and see what values livDB process writes into the DB
> cd /home/pi/liv/livDB
> tail -f livDB.log
If you don't see the value "-999" on the LCD screen, make sure that the CO2 sensor is provisioned (Value "Yes" under ON_BOARD_SENSORS_SECTION in livDB.config file). The most recent LiV image available for download is provisioned for temp/humidity and air pressure sensors, so you need to manually provision the CO2 sensor.