New LCD screen goes white but it works fine if pressed.

Ok,

My neice threw her iphone 3G at&T so I had to replace the following parts; Full front LCD screen, REAR cover, Power, mute, volume, buttons and corresponding flex cables.

Now, when I try to set the front glass into place with the body, it refuses to seat level, one corner is either sitting low, or the other 3 corners are sitting high.

BUT. the main problem I have is this, after making sure all the LCD connectors are correctly connected, the LCD is white. BUT if I press down on the front screen above where the LCDconnector is connected to the mainboard the display pops on and as long as I keep pressure applied to that spot the phone works 100% fine, but, as soon as I let off, the screen goes white again. It is almost like the connector is not staying fully connected but when I open the phone and check the connection, it is nice and tight. Anyone got any advice on this issue.