Macbook Pro No POST after LCD Replacement

MacBook Pro A1398 EMC 2674 does not display video after LCD replacement.

I am pretty sure I followed everything correctly, but yet here I am.  The new (used) screen I got for this model (SN: C02MT1KJFD58) for this MacBook Pro 15" Late 2013? model is part number 661-8310.  I don't know where to find that part number on the original screen.  Anyways, the old screen was busted, but would still light up.  Now that I have attempted to put on the new screen, I can see the screen momentarily flash (as if it is on with no backlight), but nothing displays that I can ACTUALLY see with a  flashlight.  Also, the HDMI connection displays nothing and the unit seems to power itself down after a bit.  Also, if you plug the magsafe in, it automatically turns on.  Is that normal?  I have tried hooking the old screen back up to it, but I also get no display.  HOWEVER, we attempted to remove JUST the glass from the old screen, so we may have damaged it. :(  Suggestions on how to get the new screen to work?
Scott ThompsonComputer Technician / OwnerAsked:
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That's not normal.  Double check your wiring.
Scott ThompsonComputer Technician / OwnerAuthor Commented:
I have disconnected and reconnected the battery, the LCD cable, the iSight? cable, and cleaned the MagSafe connector.  No difference.
Scott ThompsonComputer Technician / OwnerAuthor Commented:
I may have to return the screen unless anyone else has an idea.  The supplier verified with me and the serial number that this is the correction screen.  Any other ideas?
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fred hakimRetired ITCommented:
As said above, double check your screen connections.  If the new screen is good, it sounds like a skewed connector could be shorting one of the voltages.   If the new screen is bad, then the old screen should still light up (as it used to).

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Scott ThompsonComputer Technician / OwnerAuthor Commented:
I reinstalled the old screen again just to test, and this time it lit up (the undamaged part) and the system passed POST.  We are assuming the new screen is the issue.  Thank you for your help!
fred hakimRetired ITCommented:
Wouldn't hurt to try the new one one more time, just to be sure it wasn't a skewed connection.   Those little connectors are easy to mis-align -- especially if you have big fingers like me.
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