I just want to reset to factory default. But the manual doesn't teach with that.
forget switchting the light on... this is only said to make sure the light is really without power.
Basically it goes that way:
Screw on the battery tube.
As soon as the electronics notice there is voltage, they start this one-second dim light. In that one second, hold the button and wait until the brighter-dim-bright-off sequence is over.
Reset done.