My ketone has started just going black screened and unresponsive at times. I have to hold the power button for ten seconds so it resets or nothing happens. Any ideas ? Anyone?

Try a full reboot and/or safe mode:

From BB blog: How to reset PRIV by BlackBerry | Inside BlackBerry Help Blog

Three restart/reboot methods

The first method, which should be used 99.9% of the time when you want to reboot your device, is using the Reboot option that appears after pressing the Power key.

Press and hold the Power key for 3 seconds
Select Reboot from the menu that is presented

The second reset method should be used if pressing the Power key does not produce the menu with Power Off and Restart. For example, if an app or game you are using won’t close, use this option to restart your device.

Press and hold the Power key for 12 seconds

Third method: Should your device fail to respond, the final reset method is to press and hold the Power key for 32 seconds which is equivalent to removing the battery. This should result in your device booting up successfully.

If it fails to start, however, verify you are not pressing any other keys such as Volume Up, Mute, or Volume Down while performing any of the reset methods listed above. If you use a case for your device you may want to remove it as it might be pressing a button inadvertently.

And just for an extra measure, if needed:

Safe Mode:

The next step is placing your device into safe mode.

When used, Safe Mode will disable any third party apps or games you have installed. As a result of this, should your device not exhibit the issue while in Safe Mode it’s safe to assume the issue is specific to an app or game you have installed. Safe Mode may also remove apps and/or widgets from your various home screens when you go back to Normal.

Press and hold the power key
Tap and hold Power off (that is Press/Hold the Power Off prompt line) when it appears
When prompted, tap OK to reboot to Safe Mode

To get out of Safe Mode, press and hold the power key followed by tapping Reboot.

After testing, should your device not exhibit any issues, the next step is to remove recently installed applications one by one until the issue is resolved.

If that fails you might investigate reloading the OS using an Autoloader:

https://forums.crackberry.com/blackb...aders-1065667/

Hai.. i just bought my blackberry keyone black edition and started to experienced the same thing.
My screen just turn black and unresponsive. but still it can receive a call and a notification.
How is ur solution so far friend?

Any solution to this? It is so hard to prove to a retailer

I experienced this once today.. had to restart the phone by pressing the power button