No Power, No signs of any life, Replaced Multiple Parts

This iPad 2 originally came in with a cracked glass and a broken headphone jack. Both were replaced successfully and the iPad was fully functional.

Now the iPad has come back with the symptom of not turning on (no power). I replaced the Volume Power Button because there was a slight tear in the cable near the power button (thinking the power button was not functional to turn on the iPad).

I have also replaced the Dock Connector in thought that it was bad and not charging the iPad.

The device shows no signs of life when attempting to turn on with the power button nor the power and home button held down.

I have also looked under light at the LCD to be sure the backlight was just not working but nothing ever showed up on the screen.

Next step is ether a bad LCD, bad Battery, or bad LVDS cable. Does anyone have any ways to determine which is bad?