Weird ScreenWhen Trying to Clear Partition

[pjwk81]

Got an update this morning which was apparently the April security patch. As per normal I went to clear my cache partition after the update but when I tried the normal routine I got this screen up. Never seen it before. Have I downloaded a dodgy update and corrupted my device?

 

[LineKill]

You accidentally have pressed the wrong button. You accidentally held down the volume down button instead of the volume up button. Try it again holding the volume up button and it should work. When you hold the volume down button it puts the phone into download mode.

 

[pjwk81]

Ah, so I did. Thanks.