Sticky or damaged volume buttons are a primary culprit, as the phone interprets a held volume key during startup as a command to enter the bootloader. Corrupted Firmware:
A: The boot partition is missing or corrupt. Reflash boot.img via fastboot. blackberry keyone stuck in bootloader menu
If you are stuck in a specific "QDLoader 9008" mode or the Factory Reset fails, your operating system is critically damaged. You will need a Windows PC and the official BlackBerry software tools. Sticky or damaged volume buttons are a primary
Summary of causes