F6Pro Locked up & cannot Hard Reset

I came to start an activity on my F6Pro today & noticed the watch had frozen displaying the watch face. The buttons would beep when pressed but would not do anything

I held the power button to force a power off & when powered back on it remained stuck at 'Loading FIT files'.

I tried to connect it to the PC from powered off so I could delete any fit files on the watch, but again it stays at 'Loading FIT Files' & doesn't connect

So I powered it off again attempted a hard reset; holding the back/lap button while powering on. The Yes/No options to reset the watch are displayed, but the up/down buttons just beep & don't allow me to select 'yes'.

Does anyone have any suggestions how I might be able to resolve it?