If you can see status "Locked" in device´s website - Management - Licence key ...
... than please follow this steps to make it working again
1) Please upgrade the firmware to the latest version. WIKI PAGE firmware 1.36.2
2) Please set the right date and time in the device. MANUAL PAGE
3) Please upload the license file again. Try to download it via another email client, do not open it, just upload.
4) Eventually please make a factory reset. WIKI PAGE