We refurbed a Tangerine Clamshell-replaced the motherboard, new hard drive and display. When we power up, the display is black. We can hear the hard drive making its clicks and whirs so we think the motherboard and hard drive are ok. So how do we check on the display? Could it be the display cable? We put the display into another top case and putting the cables inside the handle area was a b----! Any suggestions or help would be greatly appreciated.