@Maisiemoomoo If the forced restart method hasn't worked(might be worth trying a few times) and you can't get anything other than the white screen then it points to hardware failure(the forced reboot should clear software issues), you would need to either book a repair with Sky or take it to an Apple store https://www.sky.com/help/articles/sky-mobile-phone-or-tablet-repairs .
The only other option is to connect the phone to a computer(eithe a Mac with Finder installed or a PC with iTunes installed) and try to get it into recovery mode by pressing Volume Up, Volume Down, then hold the Side Button until you see the recovery mode screen (not just the Apple logo), you should then get prompted to either update or restore(choose update to reinstall iOS without erasing data).
