Dell Venue 8 Pro 5830 - Black Screen on Power On

Hi all,

I have a Venue 8 Pro 5830. When I hold the power button for 4 seconds, I can see the screen backlight come on, but I don't get a Dell logo or Windows boot. I have taken the cover off and unplugged the battery to ensure power is completely off, but that doesn't fix it. 

Any other things I can try? Has anyone seen this problem?