Use a small amount of high-percentage Isopropyl Alcohol on a cotton swab and click the Volume Down button repeatedly to clear any debris.
Most BlackBerry KEYone devices have a locked bootloader . Unlike other Android phones, you cannot easily flash custom kernels or modified system images unless you are using a specific, signed Autoloader provided by BlackBerry (or a verified community "repack" that maintains signature integrity). How to Flash a Clean Autoloader: blackberry keyone stuck in bootloader menu repack
Hold the and Volume Down simultaneously for a full 30 seconds. Use a small amount of high-percentage Isopropyl Alcohol
If you have successfully flashed a clean Autoloader and the device still returns to the bootloader menu, you likely have a hardware fault. How to Flash a Clean Autoloader: Hold the
If you are stuck because you tried to flash a "repack" (a modified version of the factory firmware), the issue is likely a mismatch in the partition table or a locked bootloader.