Post repair the phone is non-responsive & why is battery burning hot?

After replacing the midframe and lcd, I tried to test the lcd before I glued it to the frame. It vibrated once (as it normally does on startup) and I saw the backlight turn on for a second. I believe that I must have bumped the screens flex cable while testing the screen.

Now the screen wont turn on, but the battery is burning extremely hot. The charge light does not come on once plugged into the wall and computer. I have tried all of the typical reset combinations such as the yellow button near the sim card and holding down the power and volume buttons.

I do not understand why the battery is burning up, nor why it isn't powering up at all.

Any ideas or help will be much appreciated.