Hi JS999,
According to this Link a box with the light flashing in any colour is faulty.
I would suggest you call Virgin, 150 from your Virgin phone, mobile or landline, or 0345 454 1111 from any other phone to report a fault.
When phoning choose the option to report a fault, then ignore all the options offered and you should then be placed into a queue to speak to someone.
Or you can wait for a forum team member to respond which may be 2 to 3 days.