If the reboot was just a power cycle then try a factory reset of the box.
It's only a partial system reset and not a complete factory reset. You are given 2 options,
Keep Recordings
Format Disk
Choose Keep Recordings, that means you won't lose your recordings and any planned recordings or series links you've set up, you will have to sign into your apps such as iPlayer, Prime, Netflix and ITV Hub again, also Match frame rate and Standby power consumption will go back to their default settings if you have changed them.