Blue screen saying technical fault with all channels

[leahholliday]

Blue screen with writing saying technical fault with this channel but keeps saying this on every sky channel 

[leahholliday]

I have turned of the sky Q box at the mains and kept it turned off for 10-15 minutes and now have all sky channels back 

[mirdragon]

it's been happening to ours tonight as well, full power off and still same - when it then works it takes 5 mins to change channel, get black screen but audio still playing from previous channel