Here is the for a KEYone stuck at the top of the bootloader menu:
: Sometimes low voltage causes boot loops. Leave the phone on a wall charger while in the bootloader menu for at least before attempting to reboot. Troubleshooting Persistent Bootloader Issues blackberry keyone stuck in bootloader menu top
If the above solutions don't work, you may need to perform a factory reset: Here is the for a KEYone stuck at