Simply take your P3 out of the outlet and then turn it on by clicking the power button.
Then 'power cycle' it by triple clicking the power button. Be sure that the Pandora has NOT been charging for a couple hours to fix the issue.
If 'power cycling' doesn't work, use a USB-C cable to charge the Pandora. By plugging a USB-C cable into the Pandora it will effectively jump start the device.