Connect the power supply and wait a 3-5 minutes to allow charging before trying to power up the device again. If it does not power on. Remove the charger. Hold down the power button of the device for 10 seconds. Doing so will power off the device regardless of what it was doing. Attach the charger and turn it back on, momentarily press the power button and the device will start up and turn on.
This will not reset the iPad device; that must be done as a separate step.
