Display wont turn on, iTunes says its powered

Hi,

Got an iPad here that the customer said its just not powering on. I plugged it into the PC and opened 3uTools and it wasn't turned on. I charged it for more than 24 hours waiting for life but there was none. I changed the charging port and still made no difference. So I tried a new LCD whilst it showed the Apple logo (White) it went back off after it flashed about 3 times. I have since changed the battery too and It seemed to have more power. I was able to reflash the iOS thinking it could just be a bad software glitch and it seemed to have worked. I can setup the iPad as new and seemed ok.

But after the setup when the screen timeout kicks in I cannot get it to turn the display back on. iTunes and 3uTools says its turned on but there is no display. I've tried 2 new screens now and its still the same.

Any Ideas?