In this scenario, DIY fixes are not recommended. The KeyOne is a tightly integrated device with fragile ribbon cables. If your data is not backed up, professional data recovery is your only remaining option.
If you can navigate the bootloader menu (using Volume Up/Down to move, Power to select), do this: blackberry keyone stuck in bootloader menu
Stuck in Bootloader Mode - BlackBerry Forums at CrackBerry.com In this scenario, DIY fixes are not recommended