Mechanically not particularly stable

Have the clock thermostat ordered and wanted to settle my underfloor heating in a room. The instrument was intended to replace an old analog thermostat. Internally, the device 2 boards. The first is screwed to the lower part of the wall - the other is in the cover is plugged after connecting the cable to the bottom part. The contact between the boards provide spring contacts forth ending only on relatively small contact surfaces. For me it was now so that after connection and press together the housing parts first awoke in the display thermostat to life. But if I have tried to make the settings, the thermostat went every time after a few times key press again. If you then rumgedrückt on housing, we went back to but not reliable. I have returned the device to Amazon.