Have you connected your iPad to your computer using the USB cord? That was one of the things suggested by Gabriel1 in he earlier link I gave you? Otherwise, I am unsure what else can be done.
Can you get to your multi-task Barry doing a 4-finger swipe upward? If you can, swipe your fingers to the right to find your volume panel and see if your brightness is set to max. Readjust and lower it to see if that helps.