For an STB Blocked message, there are a couple things you can try in order to get yourself reset.
Can try disabling any VPN service you might be using. Have seen this reported to help, when a VPN was involved.
Can try setting the MAC to an empty MAC, and then reseting the correct MAC again.
Check thread linked below...
http://iptvtalk.net/showthread.php?26850-STB-Bloccked-try-this
I have received a few messages reporting that the MAC change did work.