Its hard to say until its done.
There could be a second issue !
Can you not just buy the Box Set on DVD as a treat
And then you have time to resolve the HD Box issue.
Would sky not replace the Box?
Its worth calling them, they refused for me, so I left there TV package, and then got the begging calls to come back. Damage done and never missed it.
I think Sky do sell reconditioned boxes with a 12 month warrantee if I remember but don't hold me to it. Or even ebay.
I remember when I got a new box I had to call sky to match the viewing card with the box serial number. That was a few years ago.