Please make a hard reboot (hard restart) on your Konftel 70.
You can do this by holding the power button until you get a startup sound (should take 8-12 seconds).
Sometimes you need try this process more than one time.
After that you should be able to use Konftel 70 again.
Also read this information if you still have issues.
If you still have issues with your device, please contact us via this form.