broken x200 whole lid lcd swap, for a working one, now the used to be perfectly working machine does not work anymore

[unitywithin]

I have or had this perfectly working machine and this second one which had cracked screen, I wanted to use the second one with external monitor. so I swapped the screen to from the working x200 to the one which had this non working screen. The lights went up the fan goes too, but no image on the lcd. I connected it to external monitor via VGA port on laptop, and display port with ultrabay, tried to pus FN+ f7 and it does not changed to external monitor. The fan is spinning and then it speeds up and hdd seems to spin too, but no indicator of it on the icon.
When I gave up on it I reassembled the working unit. Tried to turn it on and it wont even light up. Once the lights lighted up for short period of time, so I turned it off I tried to insert hdd. Then I tried to turn it on again and nothing happened, no lights were up, just nothing. Nothing seems to be fried. Im wondering what might happened to this perfectly working laptop and how to fix at least one of them. I would really appreciate your help guys. Thank you very much and have a a beautiful day.
P.S power drain with cms battery unplugged I already tried that is my first aid I checked out the mobos for some burnt marks I have not been able to saw any.

[RealBlackStuff]

On that series you don't swap LCD, you swap the whole lid!

[unitywithin]

I apologize for my terminology, I swapped the whole lid ofcourse.

[RealBlackStuff]

Remove battery, charger and all RAM.
Then hold down the Power button for ca. 20 seconds.
Connect charger only and try to boot.
Does it beep 1-3-3-1 ?
If not, your motherboard may be faulty.
If yes, insert only 1 RAM and try to boot again.
OK now?

[unitywithin]

Hi I disabled the beeps in bios previously, and forgot to reenable them I tried the power drain method before, no luck.
This was perfectly working machine before I tried that screen with the lid on that second machine which did not displayed nothing but turned on. Is there a possibility to fix this ? 2 corpses in one day man I just checked the mobo of the one which was ok and now wont even turn on or blink, I saw no burnt chips, no apparent damage, before I put the screen back (which was originally used in this device, everything worked normal) as I said before, it turned once but nothing afterwards I would be so grateful if you can help me to revive these babies

[unitywithin]

Its so freaking weird the second device which worked perfectly always, I took it appart, inspected the mobo as I mentioned and then just with the mobo(no housing, I connected keyboard hdd and plug into it and turned it on? and it works??? wtf, now I just need to fix the second device which turns on but no image.
edit, I put all back to case, not a single sign of life, no light on nothing, Its quite maddening, Im wondering what can be the problem.

[axur-delmeria]

Let's make things clear first:

1. Bare X200 board + keyboard and HDD --> working

Question: did you connect an external monitor to check if there's any video output?

2. X200 board inside chassis with everything connected --> no power.

If that's the case, then it's best to start with #1 then install parts one by one, testing in between.

Put the X200 board into the chassis, but connect only the keyboard and HDD like before. Also connect an external monitor if you did so before. Power up the laptop.

If it works, good. Turn it off then disconnect the charger and battery.

Plug in the audio board then turn it on again to see if the laptop still works properly.

Repeat the cycle with other parts like the wifi, bluetooth, etc.

Make sure that the LCD cable is the last part to plug in.

[unitywithin]

This was the used to be 100% working device, not the one with damaged display which does not put out image to external monitor.
So I tried to unplug few things which were not plugged when it was tried barebone. The little board with audio... when I plug it in , no lights are present on the lcd (it has its own lid and lcd, the one I tried to swap to that broken machine to be able to turn it on to external display mode, its the original display of this device) First thing I noticed when I plugged the power in that it turns on by itself. Then shuts down, then when I turn it on I got stuck on the boot /set time message. Then I had to restart because keyboard was not working. Even through I got into bios setting by pushing thinkvantege button. Then when I restarted it there was those
little lights, but no image on lcd. so I decided to let it sit with cmos unplugged like I did yesterday night.
Im wondering what might be the issue with this device its really strange. Do you think that whole lcd lid swap attempt to that second device might damaged this originally perfectly working device ?
Thank you and wish you a beautiful day