The flashing light means you have a signal fault. Its telling you the box cannot establish an upstream path, which means you will not be able to access On Demand, Catch-up or interactive services. Check the service status via the link below your username top right of the page. If no area faults are shown you need to contact the faults department so they can check your levels, & this will likely result in an engineer visit being booked to resolve the issue.
Cable customer since 1993. Services: FH TV, Sky Sports & Movies (2xV+), Talk Unlim Telco, VIVID 100, Virgin PAYG Mobile