Try turning the knob one click at a time
done that

The top button should reset the button LEDs to 'Off'. Then use the knob to increase the level.

When I press the top button the lights go [OFF]
Then I slowly turn the knob one click at a time, the level increases by one with each click until it's at [6] then it jumps to [MAX]
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Greetings, Robert -- I am woman, here me roar! *meow* Bubbles