There are a few reasons that the breathalyser is not switching on
- Weak/Flat batteries.
Try replacing with a brand new set of alkaline, non-heavy duty, non-rechargeable batteries. - Calibration
The unit may be due for calibration - especially if it hasn't been calibrated in the last 6 months. You can book your unit in for a calibration here. - Chipset problem
If you have replaced the batteries and/or if the unit is brand new or calibrated in the last 6 months then there could be an issue with the chipset. Please contact us by clicking on "New Support Ticket" above for further assistance.