If you have rebooted the box by switching the power off and on again with either the switch on the back of the box or at the plug and has made no difference try a factory reset.
The factory reset has 2 options it's only a partial system reset and not a complete factory reset if you select the Keep recordings option.
These are the factory reset options.
Keep Recordings
Format Disk
If you choose the Keep Recordings option that means you won't lose your recordings and any planned recordings or series links you've set up, but you will have to sign into your apps such as iPlayer, Prime, Netflix and ITVX again, also Match frame rate and Standby power consumption will go back to their default settings if you have changed them.
