Cable box

5:00 is the code that the box gives when it isn't getting any cable signal, or at least signal below its ability to detect.

When you say the "power went out" do you mean just on the box, or all the electricity in the house/room/outlet? If the latter, then my guess is you have a cable signal booster somewhere in your house and it lost power with the black out?

Either that, or maybe someone hit a telephone pole. Do you have any TVs in your house that use cable but without a box? Do those work?