Device: HTS9221

Since a couple of days, all touch buttons: navigation, volume, eject etcetera, disappeared from the front top of the device.
Only the On/Off button is visible.
The equivalent buttons on the remote control still work properly.
The front top buttons normally were lid, but for some reason they don't appear anymore.
The device has the latest software update installed.

Some technical advice, on how to solve this problem, is much appreciated.