The magic cube

It is a present from my wife and located on my desk. A designer cube made of wood, displaying time and temperature.

Wonderful and with a bit of hidden magic. How to activate the display, which will then disappear after a few seconds ? The short manual does not really help (a very bad translation from chinese, as in former times) and the function of the 3 buttons on the back is not clear either.

What I found out over time: knocking on the desk is the solution, as the cube works with a sort of vibration sensor.