iPhone 5 dark backlights. but can receive calls responds to touch

History of the problem. My battery dont last long. I ordered a new battery and the battery happened to be fake. After installing the new battery and when charging it. The battery never increased instead it was decreasing. So i opened it again and again and put back the old battery, but the old Battery work just fine. So i tried back the new battery but the same problem. So i decide to put back the old battery but this time a kind of line appeared on the screen. I was suspecting the connecting cable to the logic board, so i keep on pressing it to seat well. But the line somehow disappeared and come back. So i just removed the cable totally blow air to the logic board Put it back but it never displayed anything again.

I could hear Charging sound or vibration if switch to silent when plugin to charger. Even if its off it will on automatic, and i can hear the sleep/wake when i press the power button and screen shot sound when press the power and home button. The phone getting really hot (heatup)from the logic board.

But the iPhone 5 backlight is not displaying, just a dark screen like as if the phone is not powered on or dead.

Earlier on i couldn't received calls, as it keep on saying phone is switch off each time i tried to call as it was formerly on airplane mode before.

So i did some research on google and i download and install itools ( itools is free) for windows and i connect my IPhone. From the itools mirror displayed on my pc i was able to see that the phone was on and can guess the spots and directions i need to touch from my iPhone to switch it from airplane mode.

So from there i removed it from airplane mode and closed all opened apps.

I can see the screen from the mirror on my pc. Everything responds when i touch the dark screen on the iPhone.

Then i called my phone and it rang and i pick the call by sliding to right at the bottom of my iphone dark screen and it works fine. As it was also showing from my pc.

Although the itools is just a screen snap but i was refreshing it and understand it well from the pc.

I have opend the iPhone and removed the battery several times. Disassembled and assembled everything, washed the logic board and dried it. But still the same problem.

I tested my screen from another working iPhone my screen displayed fine. And i tried other screen on this iphone but the same problem.

It look like the problem is from the logic board. What can i do please, someone who have experience this problem should help me out urgently.

Already tried retarting the phone with home and power button but no solution.

Thanks.