iPod's LCD dead after replacement..

Hello guys:-) Big problem here..I tried two difference LCD + touchscreen with this ipod 4th. The LCD is showing nothing... i mean like the ipod is powered off. In fact the only problem was the broken touchscreen.

Today after few tries with different LCD they don't work.... i noticed that the LCD cable doesn't "sits" properly on the connector but when it stays the LCD looks even black and dead.... What can i do??? The ipod is recognized by the computer and seems to work and it becomes hot, so that's fine.

let me know pleaseeeee