The AlcoSense Nexus Breathalyser has a pull-off back cover, once opened you can find the serial number inside.

1. Locate the groove at the bottom of the unit:

2. Using your fingernails, lift the cover up from that groove

3. If there appears to be force holding the cover down, wiggle it from side to side to loosen it

4. Then lift the cover completely using a little force.

This should not snap or damage the cover if done right. 

*Serial number is at the back of the unit after removing the back cover.

Should you require any further assistance, please feel free to contact us at support@andatech.com.au