Obviously /g/ sticky sent me there.

I be having some weird issues with a laptop I'm trying to fix or rather gave up.
Generally my sister complained it stopped working and didn't mind that but would be nice to do that.
Quick diagnosis and shi - charging port dead.
Bought a donor mobo with a charging port as parts were scarce for this model and well it was an okay deal.
Replaced the charging port on sister's lappy and still no boot, no reaction other than at least battery light giving a sign of life each 30 seconds or so.
Thought to myself that I'd try booting the donor mobo out of curiosity and it launched perfectly fine.
Quick decision to swap components between both of these to make one working laptop out of those and voila
It doesn't work.
Around 2-3h wasted getting nowhere before I decide to remove component one by one.
And voila - computer boots or at least the fan spins.
Bad news - it only does that when the internal display is disconnected and automatically without the push of a button.
And I've been thinking what the hell is wrong with it and came with like 4-5 options
1. I messed up at disassembly and assembly
2. It messed itself up overnight
3. Both
4. Display is trash
5. Display isn't trash but might have ID or something in itself refusing to work with another board?
6. All of the above

In case of the display it's connected with two plugs. One golden plated or with gold pins which was held with ducttape originally and goes in the port and another black 6-7 pin connector similar to pwm fans in case of look.
What are your thoughts anons?
What may be borked?

I'm thinking of giving up on it (honestly done that yesterday) and telling my sister that I'll get her another laptop and call it a day.
This one worked still quite long considering it was in a trash condition and she managed to force 3,5mm jack into a usb port.

TLDR : Laptop only works without internal display
Thanks anons