Screen stays black phone vibrates iTunes recognizes phone, Reassembled

TLDR version below!

Hi,

I have gotten a friends iPhone 5s for free he got it bend and the screen cracked.

I hooked up a working 5s screen to see if it still worked, and it did!

Told my friend about it incase he had any important data left on it, told me i could keep it for spare parts.

After some thought on what to do with the phone, i figured why not just fix it and sell it.

I came across a cheap screen bought it immediately . Only the housing left i looked for one on Aliexpress and went for something different, an iPhone 6 housing case.

Once everything was in place it was time to build it up, everything was fitting nicely and all was good. Until i snapped the Home Button ribbon cable per accident, bye bye iTouch functionality :'(.

So after buying a new home button and replacing that i tested the screen once more before tightening everything up. It worked so i proceeded to slide the screen in place when it suddenly shut down. After this point it would not come on no matter what i tried. My immediate taught was i ripped the LCD ribbon cable or cracked the screen.

I have another 5s lying around, so opened that one up to test the screen. And it was still operational. So the iPhone 5s now turns on gets recognized by iTunes, can make a screenshot but the screen wont come on.

So now i am lost on what the cause of it can be, i took a better look and found a small difference on the mainboard with the other 5s i have lying around.

I have the feeling i might have fried something :S.

See pictures for details.

Other working iPhone 5s Mainboard

http://i65.tinypic.com/1zgufb4.jpg

Reassembled iPhone 5s Motherboard

http://i65.tinypic.com/o03148.jpg

Long story short!

Reassembled iPhone 5s, screen will not turn on LCD is not broken

Screen was tested and worked on an other 5s.

Phone gets recognized by iTunes and vibrates makes all the right noises!

Slight difference on mainboard with another 5s i have. See pictures for that!