Try doing a hard reset by holding the power button down for 8 seconds. If this did not work for you, then refer to link below. HP 7 Plus 1302 Troubleshooting

There could be a problem with the headphones themselves. Try testing them on another device. If the problem still occurs refer to the link below for additional solutions. HP 7 Plus 1302 Troubleshooting

Plug charger back into your device and let it charge for about ten minutes, Then hold down the power button until either the battery show on the screen or until it power back up. If the battery displays on the black screen that means your device doesn't have enough charge to power up. If the problem is still not resolved refer to link below. HP 7 Plus 1302 Troubleshooting