... will stop working. When it is ON, press the centre button, it will show battery voltage, for example, 3.7V will display ... .5s to confirm the choice.3.1 Under the "1.dR"mode, press the big button again, the display shall show the resistance of the Cartomizer/atomizer ... ”. if without Cartomizer/atomizer, it will show F1.3.2 Under the "2.dU"mode, press the "-" or "+" button to adjust voltage up ...