1. The display needs to enter the brightness programming mode. To do this, press and hold the BATT button; the display will show the battery voltage.
2. While continuing to hold the BATT button, press and hold the GREY button. Continue to hold both buttons for approximately 5 seconds until the display shows “bri” to indicate the brightness programming mode. When this occurs, release both buttons.
3. Press the GREY tank button to increase brightness, or the FRESH tank button to decrease brightness.
4. When the display shows the correct brightness, press the BATT button to exit the programming mode.