Well there's nothing you can do, it's broken and will need replacing. Quickest option is a box swap delivered. There are normally only 4 cables to connect (2 satellite feed, 1 power, 1 HDMI) and you have to make sure you keep your viewing card. Note: there are two types of power cords for different variants of these Q boxes. One with an external power brick and one without. Make sure the replacement box matches or if not, that you also swap the power cable.
a wait for an engineer will take a lot longer I suspect
anyway, start here https://www.sky.com/help/articles/sky-box-problems
