Unusual problem - Samsung Tab screen is black after I lock it

Please help !! My Tab has an unusual problem. I have a Samsung Galaxy 2014 10.1in Tab.

I have tried all the hard reset options of Power button + Volume keys. Screen turns ON and works normally after the restart. However if the screen locks out or if I lock it, the screen will not show a display even after I press the home button or power button. The battery is almost 100% and I know the screen is ON because I can feel the haptic feedback when I try to swipe my pattern (I know location of pattern on screen even when it is blank).

I have reset the tablet to factory settings - same problem reoccurs.

I have used the Samsung Kies software on my computer to reset the tab a second time - still no luck. The screen is ON and works great the first time after a restart. However, once I lock the screen, it doesn't show up again.