iPhone 6 problem

My iPhone 6 32gb (less than a month old) has gone to a black screen after I plugged in an aux cable.

The aux was having problems the other day, and didn't work earlier today when I plugged it into my laptop. I attempted to press the unlock button just after I plugged the cable in and the screen has gone black, and none of the buttons are working.

Unsure of how to proceed/what the issue even is. Any help is much appreciated