Up/down

Due to a little dot on one of the buttons, you feel the difference between up and down.

1. Press both arrowed buttons at the same time for 3 seconds.
2. Continue pressing the buttons until both columns are in its lowest position. Keep pressing the buttons until control box makes 1 beep.
3. When the control box makes 1 beep, it is confirmed that a reset has been completed and the buttons can be released.
4. Now the desk is operational.